<PAGE>   1

                                                                   EXHIBIT 10.12


                                 AMENDMENT NO. 3
                         Dated as of September 28, 1998
                                       to
                      TRANSFER AND ADMINISTRATION AGREEMENT
                           Dated as of August 28, 1997


                  THIS AMENDMENT NO. 3 (this "AMENDMENT") dated as of September
28, 1998 is entered into by and among NMC FUNDING CORPORATION, a Delaware
corporation, as Transferor (the "TRANSFEROR"), NATIONAL MEDICAL CARE, INC., a
Delaware corporation, as the initial "COLLECTION AGENT", ENTERPRISE FUNDING
CORPORATION, a Delaware corporation (the "COMPANY"), and NATIONSBANK, N.A., a
national banking association ("NATIONSBANK"), as agent for the Company and the
Bank Investors (in such capacity, the "AGENT") and as a Bank Investor.

                              PRELIMINARY STATEMENT

                  A.       The Company, the Transferor, the Collection Agent and
NationsBank, in its capacity as the Agent and as a Bank Investor, are parties to
that certain Transfer and Administration Agreement dated as of August 28, 1997
(as amended or otherwise modified prior to the date hereof, the "TAA").
Capitalized terms used herein and not otherwise defined shall have the meanings
ascribed to them in the TAA.

                  B.       The Company, the Transferor, the Collection Agent and
NationsBank, as Agent and as a Bank Investor, have agreed to amend the TAA on
the terms and conditions hereinafter set forth.

                  NOW, THEREFORE, in consideration of the premises set forth
above, and other good and valuable consideration the receipt and sufficiency of
which is hereby acknowledged, the parties hereto agree as follows:

                  SECTION 1. AMENDMENTS TO THE TAA. Subject to the satisfaction
of the conditions precedent set forth in Section 2 below, the TAA is amended as
follows:

                  1.1.     The definition of "COMMITMENT TERMINATION DATE" set
         forth in Section 1.1 of the TAA is amended to change the date set forth
         therein from "September 28, 1998" to "September 27, 1999".



<PAGE>   2

                  1.2.     The definition of "TERMINATION DATE" set forth in
         Section 1.1 of the TAA is amended to change the date set forth in
         clause (viii) thereof from "September 28, 1998" to "September 27,
         1999".

                  1.3.     The following new definitions are added to Section
         1.1 of the TAA in appropriate alphabetical order:

                           "RECEIVABLE SYSTEMS" has the meaning specified in
                  Section 3.1(aa).

                           "YEAR 2000 COMPLIANT" has the meaning specified in
                  Section 3.1(aa).

                  1.4.     Section 3.1 of the TAA is amended to add, immediately
         after paragraph (z), the following new paragraph (aa):

                           "(aa) YEAR 2000 COMPLIANCE. The Transferor has (i)
                  initiated a review and assessment of all areas within its and
                  each of its Subsidiaries' business and operations (including
                  those affected by suppliers, vendors and customers) that could
                  be adversely affected by the 'Year 2000 Problem' (that is, the
                  risk that computer applications used by the Transferor or any
                  of its Subsidiaries (or suppliers, vendors and customers) may
                  be unable to recognize and perform properly date-sensitive
                  functions involving certain dates prior to and any date after
                  December 31, 1999), (ii) initiated the development of a plan
                  and timeline for addressing the Year 2000 Problem on a timely
                  basis, and (iii) to date, implemented that plan in accordance
                  with that timetable. The Transferor believes that all computer
                  applications (including those of its suppliers, vendors and
                  customers) that are material to its or any of its
                  Subsidiaries' business and operations are reasonably expected
                  on a timely basis to be able to perform properly
                  date-sensitive functions for all dates before and after
                  January 1, 2000 (that is, be 'Year 2000 Compliant'), except to
                  the extent that a failure to do so could not reasonably be
                  expected (a) to have a Material Adverse Effect on the
                  Transferor or on the transaction documented under this
                  Agreement, or (b) to result in a Termination Event.

                  The Transferor (i) has initiated a review and assessment of
                  all computer applications (including, but not limited to,
                  those of the Transferor, the Collection Agent, the Seller, any
                  Transferring Affiliate and any of their respective suppliers,
                  vendors, customers or third party servicers), which are
                  related to or involved in the origination, collection,
                  management or servicing of the Receivables (the 'Receivable
                  Systems') and (ii) believes that such Receivable Systems are
                  Year 2000 Compliant or will be Year 2000 Compliant on or
                  before April 1, 1999 and thereafter.


<PAGE>   3

                  The Company believes that the costs of all assessment,
                  remediation, testing and integration related to the
                  Transferor's plan for becoming Year 2000 Compliant will not
                  have a material adverse effect on the financial condition or
                  operations of the Transferor."

                  1.5.     Section 3.3 of the TAA is amended to add, immediately
         after paragraph (k), the following new paragraph (l):

                           "(l) YEAR 2000 COMPLIANCE. The Collection Agent has
                  (i) initiated a review and assessment of all areas within its,
                  the Seller's and each Transferring Affiliate's business and
                  operations (including those affected by suppliers, vendors and
                  customers) that could be adversely affected by the 'Year 2000
                  Problem' (that is, the risk that computer applications used by
                  the Collection Agent, the Seller or any Transferring Affiliate
                  (or suppliers, vendors and customers) may be unable to
                  recognize and perform properly date-sensitive functions
                  involving certain dates prior to and any date after December
                  31, 1999), (ii) initiated the development of a plan and
                  timeline for addressing the Year 2000 Problem on a timely
                  basis, and (iii) to date, implemented that plan in accordance
                  with that timetable. The Collection Agent believes that all
                  computer applications (including those of its suppliers,
                  vendors and customers) that are material to its, the Seller's
                  or any Transferring Affiliate's business and operations are
                  reasonably expected on a timely basis to be Year 2000
                  Compliant, except to the extent that a failure to do so could
                  not reasonably be expected (a) to have a Material Adverse
                  Effect on the Collection Agent, the Seller or any Transferring
                  Affiliate or on the transactions contemplated by the
                  Transaction Documents, or (b) to result in a Termination
                  Event.

                  The Collection Agent (i) has initiated a review and assessment
                  of all Receivable Systems and (ii) believes that such
                  Receivable Systems are Year 2000 Compliant or will be Year
                  2000 Compliant on or before April 1, 1999 and thereafter.

                  The Collection Agent believes that the costs of all
                  assessment, remediation, testing and integration related to
                  the Collection Agent's plan for becoming, and causing the
                  Seller and each Transferring Affiliate to become, Year 2000
                  Compliant will not have a material adverse effect on the
                  financial condition or operations of the Collection Agent, the
                  Seller or any Transferring Affiliate."

                  1.6.     Section 5.1 of the TAA is amended to add, immediately
         following paragraph (n), the following new paragraphs (o) and (p):

                           "(o) YEAR 2000 COMPLIANCE: REPORTING. The Transferor
                  will promptly notify the Agent in the event the Transferor
                  discovers or



<PAGE>   4
                  determines that any computer application (including those of
                  its suppliers, vendors and customers) (i) that is necessary
                  for the origination, collection, management, or servicing of
                  the Receivables will not be Year 2000 Compliant on or before
                  April 1, 1999 and thereafter, or (ii) that is otherwise
                  material to its or any of its Subsidiaries' business and
                  operations will not be Year 2000 Compliant on a timely basis,
                  except to the extent that, in the case of (ii) above, such
                  failure could not reasonably be expected (a) to have a
                  Material Adverse Effect on the Transferor or on the
                  transaction documented under this Agreement, or (b) to result
                  in a Termination Event.

                  Further, the Transferor will deliver simultaneously with any
                  quarterly or annual financial statements or reports to be
                  delivered under the Agreement, a certificate signed by an
                  officer of the Transferor that no material event, problems or
                  conditions have occurred which in the opinion of management
                  would (i) prevent or materially delay the Transferor's plan to
                  become Year 2000 Compliant or (ii) cause or be likely to cause
                  the Transferor's representations and warranties or covenants
                  with respect to being or becoming Year 2000 Compliant to no
                  longer be true.

                           (p)      YEAR 2000 COMPLIANCE: IMPLEMENTATION: The
                  Transferor will cause (i) all computer applications (including
                  those of its suppliers, vendors and customers) that are
                  material to its or any of its Subsidiaries' business and
                  operations to be Year 2000 Compliant on a timely basis, except
                  to the extent that a failure to do so could not reasonably be
                  expected (a) to have a Material Adverse Effect on the
                  Transferor or on the transaction documented under this
                  Agreement, or (b) to result in a Termination Event; and (ii)
                  all Receivable Systems to be Year 2000 Compliant at all times
                  on and after April 1, 1999. The Transferor will deliver a
                  certificate to the Agent, signed by the chief information
                  officer of the Transferor, certifying compliance with the
                  foregoing covenant by no later than April 1, 1999."

                  1.7.     Section 5.3 of the TAA is amended to add, immediately
         following paragraph (h), the following new paragraphs (i) and (j):

                           "(i) YEAR 2000 COMPLIANCE: REPORTING. The Collection
                  Agent will promptly notify the Agent in the event the
                  Collection Agent discovers or determines that any computer
                  application (including those of its suppliers, vendors and
                  customers) (i) that is necessary for the origination,
                  collection, management, or servicing of the Receivables by the
                  Collection Agent, the Seller or any Transferring Affiliate
                  will not be Year 2000 Compliant on or before January 1, 1999
                  and thereafter, or (ii) that is otherwise material to its or
                  the Seller's or any Transferring Affiliate's business and
                  operations will not be Year 2000 Compliant on a timely basis,
                  except to the extent 


<PAGE>   5


                  that, in the case of (ii) above, such failure could not
                  reasonably be expected (a) to have a Material Adverse Effect
                  on the Collection Agent, the Seller or any Transferring
                  Affiliate or on the transactions contemplated under the
                  Transaction Documents, or (b) to result in a Termination
                  Event.

                  Further, the Collection Agent will deliver simultaneously with
                  any quarterly or annual financial statements or reports to be
                  delivered under the Agreement, a certificate signed by an
                  officer of the Collection Agent that no material event,
                  problems or conditions have occurred which in the opinion of
                  management would (i) prevent or materially delay the
                  Collection Agent's plan to become, and to cause the Seller and
                  each Transferring Affiliate to become, Year 2000 Compliant or
                  (ii) cause or be likely to cause the Collection Agent's
                  representations and warranties or covenants with respect to
                  the Collection Agent, the Seller and each Transferring
                  Affiliate being or becoming Year 2000 Compliant to no longer
                  be true.

                           (j)      YEAR 2000 COMPLIANCE: IMPLEMENTATION: The
                  Collection Agent will cause (i) all computer applications
                  (including those of its suppliers, vendors and customers) that
                  are material to its or any of its Subsidiaries' business and
                  operations to be Year 2000 Compliant on a timely basis, except
                  to the extent that a failure to do so could not reasonably be
                  expected (a) to have a Material Adverse Effect on the
                  Collection Agent or on the transaction documented under this
                  Agreement, or (b) to result in a Termination Event; and (ii)
                  all Receivable Systems to be Year 2000 Compliant at all times
                  on and after April 1, 1999. The Collection Agent will deliver
                  a certificate to the Agent, signed by the chief information
                  officer of the Collection Agent, certifying compliance with
                  the foregoing covenant by no later than April 1, 1999."

                  1.8.     Section 8.1 of the TAA is amended (a) to replace the
         period appearing at the end of clause (xx) with a semicolon followed by
         the word "or" and (b) to add the following new clause (xxi):

                           "(xxi) any failure of the computer applications of
                  the Transferor, the Seller, the Collection Agent or any
                  Transferring Affiliate (including those of suppliers, vendors
                  and customers and the Receivables Systems) to be Year 2000
                  Compliant at any time."

                  SECTION 2. CONDITIONS PRECEDENT. This Amendment shall become
effective and be deemed effective as of the date hereof upon the receipt by the
Agent of each of the following:

                  (i)      counterparts of this Amendment duly executed by the
Company, the Transferor, the Collection Agent, the Bank Investor and the Agent;


<PAGE>   6

                  (ii)     counterparts of an Amendment, in substantially the
form of Exhibit A attached hereto, to the Receivables Purchase Agreement, duly
executed by each of the Seller and the Transferor; and

                  (iii)    a reaffirmation of the Parent Agreement,
substantially in the form of Exhibit B attached hereto, duly executed by each of
FMC and FMCH.

                  SECTION 3. COVENANTS, REPRESENTATIONS AND WARRANTIES OF THE
TRANSFEROR AND THE COLLECTION Agent.

                  3.1      Upon the effectiveness of this Amendment, each of the
Transferor and the Collection Agent hereby reaffirms (subject to the
modifications to Exhibit H to the TAA set forth in the Certificate of even date
herewith executed by the Transferor and the Collection Agent) all covenants,
representations and warranties made by it in the TAA and agrees that all such
covenants, representations and warranties shall be deemed to have been remade as
of the effective date of this Amendment.

                  3.2      Each of the Transferor and the Collection Agent
hereby represents and warrants that (i) this Amendment constitutes the legal,
valid and binding obligation of such party, enforceable against it in accordance
with its terms and (ii) upon the effectiveness of this Amendment, no Termination
Event or Potential Termination Event shall exist under the TAA.

                  SECTION 4. REFERENCE TO AND EFFECT ON THE TAA; CONSENT TO
AMENDMENT OF RECEIVABLES PURCHASE AGREEMENT.

                  4.1      Upon the effectiveness of this Amendment, each
reference in the TAA to "this Agreement," "hereunder," "hereof," "herein,"
"hereby" or words of like import shall mean and be a reference to the TAA as
amended hereby, and each reference to the TAA in any other document, instrument
and agreement executed and/or delivered in connection with the TAA shall mean
and be a reference to the TAA as amended hereby.

                  4.2      Except as specifically amended hereby, the TAA and
all other documents, instruments and agreements executed and/or delivered in
connection therewith shall remain in full force and effect and are hereby
ratified and confirmed.

                  4.3      The execution, delivery and effectiveness of this
Amendment shall not operate as a waiver of any right, power or remedy of the
Company, the Bank Investor or the Agent under the TAA or any other document,
instrument, or agreement executed in connection therewith, nor constitute a
waiver of any provision contained therein.


<PAGE>   7

                  4.4      The Company and NationsBank, as a Bank Investor and
as Agent, hereby consent to the execution by the Transferor of an Amendment to
the Receivables Purchase Agreement in substantially the form attached as Exhibit
A.

                  SECTION 5. GOVERNING LAW. THIS AMENDMENT SHALL BE GOVERNED AND
CONSTRUED IN ACCORDANCE WITH THE INTERNAL LAWS (AS OPPOSED TO THE CONFLICT OF
LAW PROVISIONS) AND DECISIONS OF THE STATE OF NEW YORK.

                  SECTION 6. EXECUTION IN COUNTERPARTS. This Amendment may be
executed in any number of counterparts and by different parties hereto in
separate counterparts, each of which when so executed and delivered shall be
deemed to be an original and all of which taken together shall constitute but
one and the same instrument.

                  SECTION 7. HEADINGS. Section headings in this Amendment are
included herein for convenience of reference only and shall not constitute a
part of this Amendment for any other purpose.





<PAGE>   8

                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be executed by their respective officers thereunto duly authorized
as of the date first written above.


                                   ENTERPRISE FUNDING CORPORATION,
                                   as Company


                                   By: /s/ Stewart Cutler
                                       --------------------------------------- 
                                       Stewart Cutler
                                       Vice President




                                   NMC FUNDING CORPORATION,
                                   as Transferor


                                   By: /s/ James V. Luther
                                       --------------------------------------- 
                                       James V. Luther
                                       Assistant Treasurer



                                   NATIONAL MEDICAL CARE, INC.,
                                   as Collection Agent


                                   By: /s/ James V. Luther
                                       --------------------------------------- 
                                       James V. Luther
                                       Assistant Treasurer



                                   NATIONSBANK, N.A., 
                                   as Agent and as a Bank Investor


                                   By: /s/ Elliott T. Lemon
                                       --------------------------------------- 
                                       Elliott T. Lemon
                                       Vice President





                                 Signature Page
                                 Amendment No. 3

<PAGE>   9


                                                                       EXHIBIT A


                              FORM OF AMENDMENT TO
                         RECEIVABLES PURCHASE AGREEMENT

                                   (Attached)


<PAGE>   10

                                    AMENDMENT
                         Dated as of September 28, 1998
                                       to
                         RECEIVABLES PURCHASE AGREEMENT
                           Dated as of August 28, 1997


                  THIS AMENDMENT (this "AMENDMENT") dated as of September 28,
1998 is entered into by and between NMC FUNDING CORPORATION, a Delaware
corporation, as Purchaser (the "PURCHASER") and NATIONAL MEDICAL CARE, INC., a
Delaware corporation, as Seller (the "SELLER").

                              PRELIMINARY STATEMENT

                  A.       The Purchaser and the Seller are parties to that
certain Receivables Purchase Agreement dated as of August 28, 1997 (as amended
or otherwise modified prior to the date hereof, the "RPA"). Capitalized terms
used herein and not otherwise defined shall have the meanings ascribed to them
in the RPA.

                  B.       The Purchaser and the Seller have agreed to amend the
RPA on the terms and conditions hereinafter set forth.

                  NOW, THEREFORE, in consideration of the premises set forth
above, and other good and valuable consideration the receipt and sufficiency of
which is hereby acknowledged, the parties hereto agree as follows:

                  SECTION 1. AMENDMENTS TO THE RPA. Subject to the satisfaction
of the conditions precedent set forth in Section 2 below, the RPA is amended as
follows:

                  1.1.     The following new definitions are added to Section
1.1 of the RPA in appropriate alphabetical order:

                  "RECEIVABLE SYSTEMS" has the meaning specified in Section
3.1(z).

                  "YEAR 2000 COMPLIANT" has the meaning specified in Section
3.1(z).



<PAGE>   11

                           1.2.     Section 3.1 of the RPA is amended to add,
         immediately after paragraph (y), the following new paragraph (z):

                  "(z) YEAR 2000 COMPLIANCE. The Seller has (i) initiated a
         review and assessment of all areas within its and each of its
         Subsidiaries' business and operations (including those affected by
         suppliers, vendors and customers) that could be adversely affected by
         the 'Year 2000 Problem' (that is, the risk that computer applications
         used by the Seller or any of its Subsidiaries (or suppliers, vendors
         and customers) may be unable to recognize and perform properly
         date-sensitive functions involving certain dates prior to and any date
         after December 31, 1999), (ii) initiated the development of a plan and
         timeline for addressing the Year 2000 Problem on a timely basis, and
         (iii) to date, implemented that plan in accordance with that timetable.
         The Seller believes that all computer applications (including those of
         its suppliers, vendors and customers) that are material to its or any
         of its Subsidiaries' business and operations are reasonably expected on
         a timely basis to be able to perform properly date-sensitive functions
         for all dates before and after January 1, 2000 (that is, be 'Year 2000
         Compliant'), except to the extent that a failure to do so could not
         reasonably be expected (a) to have a Material Adverse Effect on the
         Seller or on the transaction documented under this Agreement, or (b) to
         result in a Termination Event.

         The Seller (i) has initiated a review and assessment of all computer
         applications (including, but not limited to those of the Seller, any
         Transferring Affiliate and any of their respective suppliers, vendors,
         customers or third party servicers), which are related to or involved
         in the origination, collection, management or servicing of the
         Receivables (the 'Receivable Systems') and (ii) believes that such
         Receivable Systems are Year 2000 Compliant or will be Year 2000
         Compliant on or before April 1, 1999 and thereafter.

         The Seller believes that the costs of all assessment, remediation,
         testing and integration related to the Seller's plan for becoming Year
         2000 Compliant will not have a material adverse effect on the financial
         condition or operations of the Seller."

                  1.3.     Section 5.1 of the RPA is amended to add, immediately
following paragraph (m), the following new paragraphs (n) and (o):

                  "(n) YEAR 2000 COMPLIANCE: REPORTING. The Seller will promptly
         notify the Agent in the event the Seller discovers or determines that
         any computer application (including those of its suppliers, vendors and
         customers) (i) that is necessary for the origination, collection,
         management, or servicing of the Receivables will not be Year 2000
         Compliant on or before April 1, 1999 and thereafter, or (ii) that is
         otherwise material to its or any of its Subsidiaries' business and
         operations will not be Year 2000 Compliant on a timely basis, except to
         the extent that, in the case of (ii) above, such failure could not


<PAGE>   12

         reasonably be expected (a) to have a Material Adverse Effect on the
         Seller or on the transaction documented under this Agreement, or (b) to
         result in a Termination Event.

         Further, the Seller will deliver simultaneously with any quarterly or
         annual financial statements or reports to be delivered under the
         Agreement, a certificate signed by an officer of the Seller that no
         material event, problems or conditions have occurred which in the
         opinion of management would (i) prevent or materially delay the
         Seller's plan to become Year 2000 Compliant or (ii) cause or be likely
         to cause the Seller's representations and warranties or covenants with
         respect to being or becoming Year 2000 Compliant to no longer be true.

                  (o)      YEAR 2000 COMPLIANCE: IMPLEMENTATION: The Seller will
         cause (i) all computer applications (including those of its suppliers,
         vendors and customers) that are material to its or any of its
         Subsidiaries' business and operations to be Year 2000 Compliant on a
         timely basis, except to the extent that a failure to do so could not
         reasonably be expected (a) to have a Material Adverse Effect on the
         Seller or on the transaction documented under this Agreement, or (b) to
         result in a Termination Event; and (ii) all Receivable Systems to be
         Year 2000 Compliant at all times on and after April 1, 1999. The Seller
         will deliver a certificate to the Seller and the Agent, signed by the
         chief information officer of the Seller, certifying compliance with the
         foregoing covenant by no later than April 1, 1999."

         1.4.     Section 8.1 of the RPA is amended (a) to replace the period
appearing at the end of clause (xviii) with a semicolon followed by the word
"or" and (b) to add the following new clause (xix):

                  "(xix) any failure of the computer applications of the Seller
         or any Transferring Affiliate(including those of suppliers, vendors and
         customers of the Seller or any Transferring Affiliate and the
         Receivables Systems) to be Year 2000 Compliant at any time."

                  SECTION 2. CONDITIONS PRECEDENT. This Amendment shall become
effective and be deemed effective as of the date hereof upon the receipt by the
Agent of each of the following:

                  (i)      counterparts of this Amendment duly executed by the
Purchaser and the Seller; and

                  (ii)     a reaffirmation of the Parent Agreement,
substantially in the form of Exhibit A attached hereto, duly executed by each of
FMC and FMCH.

                  SECTION 3. COVENANTS, REPRESENTATIONS AND WARRANTIES OF THE
SELLER.



<PAGE>   13

                  3.1      Upon the effectiveness of this Amendment, the Seller
hereby reaffirms (subject to the modifications to Exhibit F to the RPA set forth
in the Certificate of even date herewith executed by the Seller) all covenants,
representations and warranties made by it in the RPA and agrees that all such
covenants, representations and warranties shall be deemed to have been remade as
of the effective date of this Amendment.

                  3.2      The Seller hereby represents and warrants that (i)
this Amendment constitutes the legal, valid and binding obligation of such
party, enforceable against it in accordance with its terms and (ii) upon the
effectiveness of this Amendment, no Seller Default or Potential Seller Default
shall exist under the RPA.


                  SECTION 4. REFERENCE TO AND EFFECT ON THE RPA.

                  4.1      Upon the effectiveness of this Amendment, each
reference in the RPA to "this Agreement," "hereunder," "hereof," "herein,"
"hereby" or words of like import shall mean and be a reference to the RPA as
amended hereby, and each reference to the RPA in any other document, instrument
and agreement executed and/or delivered in connection with the RPA shall mean
and be a reference to the RPA as amended hereby.

                  4.2      Except as specifically amended hereby, the RPA and
all other documents, instruments and agreements executed and/or delivered in
connection therewith shall remain in full force and effect and are hereby
ratified and confirmed.

                  4.3      The execution, delivery and effectiveness of this
Amendment shall not operate as a waiver of any right, power or remedy of the
Purchaser or any of its assignees under the RPA or any other document,
instrument, or agreement executed in connection therewith, nor constitute a
waiver of any provision contained therein.

                  SECTION 5. GOVERNING LAW. THIS AMENDMENT SHALL BE GOVERNED AND
CONSTRUED IN ACCORDANCE WITH THE INTERNAL LAWS (AS OPPOSED TO THE CONFLICT OF
LAW PROVISIONS) AND DECISIONS OF THE STATE OF NEW YORK.

                  SECTION 6. EXECUTION IN COUNTERPARTS. This Amendment may be
executed in any number of counterparts and by different parties hereto in
separate counterparts, each of which when so executed and delivered shall be
deemed to be an original and all of which taken together shall constitute but
one and the same instrument.

                  SECTION 7. HEADINGS. Section headings in this Amendment are
included herein for convenience of reference only and shall not constitute a
part of this Amendment for any other purpose.



<PAGE>   14


                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be executed by their respective officers thereunto duly authorized
as of the date first written above.


                                   NMC FUNDING CORPORATION,
                                   as Purchaser


                                   By: /s/ James V. Luther
                                       ---------------------------------------- 
                                       James V. Luther



                                   NATIONAL MEDICAL CARE, INC.,
                                   as Seller


                                   By: /s/ James V. Luther
                                       ---------------------------------------- 
                                       James V. Luther






<PAGE>   15

                                                                       EXHIBIT A


                    FORM OF REAFFIRMATION OF PARENT AGREEMENT

                        REAFFIRMATION OF PARENT AGREEMENT

                               September 28, 1998


NMC Funding Corporation
Two Ledgemont Center
95 Hayden Avenue
Lexington, Massachusetts 02173

NationsBank, N.A.,
         as Agent under the
         Transfer and Administration
         Agreement referred to below
NationsBank Corporate Center--10th Floor
Charlotte, North Carolina 28255


                  Each of the undersigned, FRESENIUS MEDICAL CARE AG and
FRESENIUS MEDICAL CARE HOLDINGS, INC. (i) acknowledges, and consents to, the
execution of that certain Amendment No. 3 dated as of September 28, 1998 (the
"TAA AMENDMENT") to the Transfer and Administration Agreement, dated as of
August 28, 1997, among Enterprise Funding Corporation, NMC Funding Corporation,
National Medical Care, Inc., the "Bank Investors" parties thereto and
NationsBank, N.A., as agent, (ii) acknowledges, and consents to, the execution
of that certain Amendment dated as of September 28, 1998 (the "RPA AMENDMENT")
to the Receivables Purchase Agreement, dated as of August 28, 1997, between NMC
Funding Corporation and National Medical Care, Inc., (iii) reaffirms all of its
obligations under that certain Parent Agreement dated as of August 28, 1997 made
by the undersigned and (iv) acknowledges and agrees that, after giving effect to
the TAA Amendment and the RPA Amendment, such Parent Agreement remains in full
force and effect and such Parent Agreement is hereby ratified and confirmed.




<PAGE>   16


                                        FRESENIUS MEDICAL CARE AG


                                        By:
                                            ---------------------------------- 
                                            Title:


                                        FRESENIUS MEDICAL CARE
                                        HOLDINGS, INC.


                                        By:
                                            ---------------------------------- 
                                            Title:




<PAGE>   17

                                                                       EXHIBIT B


                    FORM OF REAFFIRMATION OF PARENT AGREEMENT

                        REAFFIRMATION OF PARENT AGREEMENT

                               September 28, 1998


NMC Funding Corporation
Two Ledgemont Center
95 Hayden Avenue
Lexington, Massachusetts 02173


NationsBank, N.A.,
         as Agent under the
         Transfer and Administration
         Agreement referred to below
NationsBank Corporate Center--10th Floor
Charlotte, North Carolina 28255


                  Each of the undersigned, FRESENIUS MEDICAL CARE AG and
FRESENIUS MEDICAL CARE HOLDINGS, INC. (i) acknowledges, and consents to, the
execution of that certain Amendment No. 3 dated as of September 28, 1998 (the
"TAA AMENDMENT") to the Transfer and Administration Agreement, dated as of
August 28, 1997, among Enterprise Funding Corporation, NMC Funding Corporation,
National Medical Care, Inc., the "Bank Investors" parties thereto and
NationsBank, N.A., as agent, (ii) acknowledges, and consents to, the execution
of that certain Amendment dated as of September 28, 1998 (the "RPA AMENDMENT")
to the Receivables Purchase Agreement, dated as of August 28, 1997, between NMC
Funding Corporation and National Medical Care, Inc., (iii) reaffirms all of its
obligations under that certain Parent Agreement dated as of August 28, 1997 made
by the undersigned and (iv) acknowledges and agrees that, after giving effect to
the TAA Amendment and the RPA Amendment, such Parent Agreement remains in full
force and effect and such Parent Agreement is hereby ratified and confirmed.



<PAGE>   18


                                        FRESENIUS MEDICAL CARE AG


                                        By:
                                            ---------------------------------- 
                                            Title:


                                        FRESENIUS MEDICAL CARE
                                        HOLDINGS, INC.


                                        By:
                                            ---------------------------------- 
                                            Title: