<PAGE>
 
                                                               EXHIBIT 10.22(ii)

                                AMENDMENT NO. 1
                                       TO
                                CREDIT AGREEMENT
                       _________________________________


          AMENDMENT NO. 1 (this "Amendment") dated as of January 21, 1998, to
                                 ---------                                   
the Credit Agreement dated as of August 28, 1997 (the "Credit Agreement"), by
                                                       ----------------      
and among CB COMMERCIAL REAL ESTATE SERVICES GROUP, INC., a Delaware corporation
(the "Company"), the BANKS (as such term is defined in the Credit Agreement),
      -------                                                                
THE SUMITOMO BANK, LIMITED, as senior managing agent for the Banks (the "Senior
                                                                         ------
Managing Agent"), BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION, as
--------------                                                              
Issuing Bank and as Agent, and WELLS FARGO BANK, N.A., BHF-BANK
AKTIENGESELLSCHAFT, CREDIT LYONNAIS LOS ANGELES BRANCH, DRESDNER BANK AG, NEW
YORK BRANCH AND GRAND CAYMAN BRANCH, and KEY BANK NATIONAL ASSOCIATION, as Co-
Agents  (collectively, the "Co-Agents"; individually, a "Co-Agent").
                            ---------                    --------   


                                    RECITALS
                                    --------

          A.   The Company has proposed to repurchase all of its outstanding
shares of Convertible Preferred Stock for a purchase price (including payment of
accrued dividends thereon) not to exceed $82,000,000 in the aggregate (the
                                                                          
"Stock Repurchase"), which shares are currently held by four institutions.
-----------------                                                         

          B.   The Company has requested that the Credit Agreement be amended to
permit, among other things, the amount of the Combined Commitments, in an
aggregate amount not to exceed $82,000,000, to be used for the Company's general
corporate purposes, including the repurchase of the Convertible Preferred Stock
of the Company and payment of accrued dividends thereon, and each of the Agent,
the Issuing Bank and the Banks is willing to agree to such amendments subject to
the terms and conditions hereinafter set forth.

          C.   Section 11.01 of the Credit Agreement provides that the Credit
Agreement may be amended after the Closing Date with the written consent of the
Company, and, in certain circumstances, the Required Banks.
<PAGE>
 
          NOW, THEREFORE, in consideration of the covenants, conditions and
agreements hereinafter set forth, and for other good and valuable consideration,
the receipt and adequacy of which are hereby acknowledged, the parties hereto
agree as follows:

SECTION 1.     RELATION TO THE CREDIT AGREEMENT; DEFINITIONS.
 
          1.1  Relation to Credit Agreement.  This Amendment constitutes an
               ----------------------------                                
integral part of the Credit Agreement.

          1.2  Capitalized Terms.  For all purposes of this Amendment,
               -----------------                                      
capitalized terms used herein without definition shall have the meanings
specified in the Credit Agreement, as said agreement shall be in effect on the
Effective Date after giving effect to this Amendment.

SECTION 2.     AMENDMENTS TO THE CREDIT AGREEMENT.

          2.1  Amendment to Section 1.01 of the Credit Agreement.  (a) Section
               -------------------------------------------------              
1.01 of the Credit Agreement is amended to add the following definitions, in
alphabetical order:

               "Amendment" means Amendment No. 1 to Credit Agreement dated as of
                ---------                                                       
          January 21, 1998 by and among the Company, the Banks, the Issuing
          Bank, the Senior Managing Agent, the Co-Agents and the Agent.

               "Stock Repurchase" has the meaning specified in the Amendment.
                ----------------                                             

               (b) Section 1.01 of the Credit Agreement is amended by deleting
each of the definitions of "Agreement," "EBITDA," "Indebtedness," "Interest
Period," "Inventory Property Loan" and "Restricted Payment" in its entirety and
replacing it with the following:

               "Agreement" means this Credit Agreement, as amended from time to
                ---------                                                      
          time.

               "EBITDA" means for any period for which the amount thereof is to
                ------                                                         
          be determined, the consolidated net income of such Person for such

                                      -2-
<PAGE>
 
          period plus the aggregate amounts deducted in determining such
                 ----                                                   
          consolidated net income in respect of (i) consolidated interest
          expense of such Person for such period, (ii) income and other taxes
          measured by income or profits of such Person for such period, and
          (iii) depreciation and amortization for such period, in each case in
          accordance with GAAP; provided, however, that consolidated net income
                                --------  -------                              
          shall be computed for these purposes without giving effect to
          extraordinary losses or extraordinary gains and without giving effect
          to any income contributed by the Inventory Property Loan.

               "Indebtedness" of any Person means, without duplication, (a) all
                ------------                                                   
          indebtedness for borrowed money; (b) all obligations issued,
          undertaken or assumed as the deferred purchase price of property or
          services (other than trade payables entered into or commissions or
          bonuses payable in the ordinary course of business on ordinary terms);
          (c) all non-contingent reimbursement or payment obligations with
          respect to Surety Instruments; (d) all obligations evidenced by notes,
          bonds, debentures or similar instruments, including obligations so
          evidenced incurred in connection with the acquisition of property,
          assets or businesses; (e) all indebtedness created or arising under
          any conditional sale or other title retention agreement, or incurred
          as financing, in either case with respect to property acquired by the
          Person (even though the rights and remedies of the seller or bank
          under such agreement in the event of default are limited to
          repossession or sale of such property); (f) all obligations with
          respect to capital leases; (g) all indebtedness referred to in clauses
          (a) through (f) above secured by (or for which the holder of such
          Indebtedness has an existing right, contingent or otherwise, to be
          secured by) any Lien upon or in property (including accounts and
          contracts rights) owned by such Person, even though such Person has
          not assumed or become liable for the payment of such Indebtedness; and
          (h) all Contingent Obligations (excluding any portion of recorded
          liabilities for legal judgments which are collateralized by cash
          secured letters of credit); provided, that, with respect to clauses
                                      --------                               
          (a), (d), (e) and (f) above, the term "Indebtedness" shall exclude the
          obligations evidenced by the Inventory Property Loan in an aggregate
          amount not to exceed $7,400,000.

          For all purposes of this Agreement, the Indebtedness of any Person
          shall include all obligations of such Person of the character
          described in 

                                      -3-
<PAGE>
 
          clauses (a) through (h) above to the extent such Person remains
          legally liable in respect thereof notwithstanding that any such
          obligation is deemed to be extinguished under GAAP, and the
          Indebtedness of any Person shall include all recourse Indebtedness of
          any partnership or joint venture or limited liability company in which
          such Person is a general partner or a joint venturer or a member.

               "Interest Period" means, as to any Offshore Rate Loan, the period
                ---------------                                                 
          commencing on the Borrowing Date of such Loan or on the
          Conversion/Continuation Date on which the Loan is converted into or
          continued as an Offshore Rate Loan, and ending on the date seven (7)
          days or one (1), two (2), three (3) or six (6) months thereafter as
          selected by the Company in its Notice of Borrowing or Notice of
          Conversion/Continuation; provided, that, the Company may only select a
                                   --------                                     
          seven (7)-day Interest Period up to six (6) times per calendar year;

     provided, further that:
     --------  -------      

               (i)  if any Interest Period would otherwise end on a day that is
          not a Business Day, that Interest Period shall be extended to the
          following Business Day unless, in the case of an Offshore Rate Loan,
          the result of such extension would be to carry such Interest Period
          into another calendar month, in which event such Interest Period shall
          end on the preceding Business Day;

               (ii) other than with respect to a seven (7) day Interest Period,
          any Interest Period pertaining to an Offshore Rate Loan that begins on
          the last Business Day of a calendar month (or on a day for which there
          is no numerically corresponding day in the calendar month at the end
          of such Interest Period) shall end on the last Business Day of the
          calendar month at the end of such Interest Period; and

               (iii)  no Interest Period for any Loan shall extend beyond the
          Revolving Termination Date.

                                      -4-
<PAGE>
 
               "Inventory Property Loan" means the obligations as evidenced by
                -----------------------                                       
          each of the Second Amended and Restated Promissory Note One dated as
          of December 30, 1994, as amended, and the Second Amended and Restated
          Promissory Note Two dated as of December 30, 1994, as amended, each
          between CB Commercial Warehouse Property Corp., a Delaware corporation
          and General Electric Capital Corporation, a New York corporation, now
          held by GELCO Corporation, a Minnesota corporation.

               "Restricted Payment" means, (a) any dividend or other
                ------------------                                  
          distribution, direct or indirect, in respect of any shares of the
          Capital Stock of the Company or any of its Subsidiaries, other than
          dividends or other distributions payable solely in shares of its
          Capital Stock, or warrants, rights, or options therefor, and dividends
          or other distributions by any of its Subsidiaries to the Company or
          another Subsidiary; and (b) any purchase, redemption, retirement or
          other acquisition of any shares of Capital Stock of the Company or any
          of its Subsidiaries, now or hereafter outstanding (except for the
          Stock Repurchase or any purchase, redemption, retirement or other
          acquisition of any shares of Capital Stock of any Subsidiary by the
          Company), or of any warrants, rights or options evidencing a right to
          purchase or acquire any such shares (except in exchange for other
          shares of Capital Stock or warrants, rights or options evidencing a
          right to purchase or acquire any such shares).

     2.2  Amendment to Section 7.12 of the Credit Agreement.  Section 7.12 of
          -------------------------------------------------                  
the Credit Agreement is amended by deleting it in its entirety and replacing it
with the following.

           7.12  Use of Proceeds. The Company shall use the proceeds of the
                 ---------------                                           
     Loans (i) to refinance a portion of outstanding indebtedness of the Company
     to The Sumitomo Bank, Limited and certain other creditors in an aggregate
     amount up to $165,000,000; (ii) to prepay a portion of outstanding
     Indebtedness of Koll in an aggregate amount up to $55,000,000 in connection
     with the Merger; (iii) to pay expenses and costs associated with the Loans
     and the Merger; and (iv) to provide for general corporate purposes
     including funding working capital needs, funding the Stock Repurchase (in
     an aggregate amount not exceeding $82,000,000), issuing letters of credit,
     and financing future acquisitions 

                                      -5-
<PAGE>
 
     not in contravention of any Requirement of Law or of any Loan Document.

     2.3 Amendment to Section 8.11 of the Credit Agreement.  Section 8.11 of the
         -------------------------------------------------                      
Credit Agreement is amended by deleting it in its entirety and replacing it with
the following:

           8.11  Maintenance of Consolidated Net Worth.  The Company shall not
                 -------------------------------------                        
     permit Consolidated Net Worth at any time to be less than the sum of (i)
     seventy-five percent (75%) of Consolidated Net Worth as of December 31,
     1997, determined on a pro forma basis to give effect to the Stock
     Repurchase (provided, that in no event shall such Consolidated Net Worth be
                 --------                                                       
     less than $57,000,000) plus (ii) seventy percent (70%) of Consolidated Net
                            ----                                               
     Income for each completed fiscal quarter beginning with the fiscal quarter
     ended March 31, 1998, for which Consolidated Net Income is a positive
     number (Consolidated Net Income for any such fiscal quarter where
     Consolidated Net Income is a loss having no effect on the calculation of
     the amount referred to in this clause (ii)), plus (iii) seventy percent
                                                  ----                      
     (70%) of any new equity issuances of the Company and its Subsidiaries after
     December 31, 1997.

SECTION 3. REPRESENTATION AND WARRANTIES OF THE COMPANY.

      3.1  Representations and Warranties.   To induce each of the Agent, the
           ------------------------------                                    
Issuing Bank and the Banks to execute and deliver this Amendment (which
representations shall survive the execution and deliver of this Amendment), the
Company represents and warrants to each of the Agent, the Issuing Bank and the
Banks that:
 
           (a)  Authority. This Amendment has been duly authorized, executed and
                ----------                                                      
delivered by it and this Amendment constitutes the legal, valid and binding
obligation, contract and agreement of the Company enforceable against it in
accordance with its terms, except as enforcement may be limited by bankruptcy,
insolvency, reorganization, moratorium or similar laws or equitable principles
relating to or limiting creditors' rights generally;

           (b) Validity of Amendment.   The Loan Documents, as amended by this
               ----------------------                                         
Amendment, constitute the legal, valid and binding obligations, contracts and
agreements of the Company enforceable against it in accordance with their
respective terms, except 

                                      -6-
<PAGE>
 
as enforcement may be limited by bankruptcy, insolvency, reorganization,
moratorium or similar laws or equitable principles relating to or limiting
creditors' rights generally;

          (c) Authorization; No Violation.   The execution, delivery and
              ----------------------------                              
performance by the Company of this Amendment (i) has been duly authorized by all
requisite corporate action and, if required, shareholder action, (ii) does not
require the consent or approval of any governmental or regulatory body or
agency, and (iii) will not (A) violate (1) any provision of law, statute, rule
or regulation or its certificate of incorporation or bylaws, (2) any order of
any court or any rule, regulation or order of any other agency or government
binding upon it, or (3) any provision of any material indenture, agreement or
other instrument to which it is a party or by which its properties or assets are
or may be bound, or (B) result in a breach or constitute (alone or with due
notice or lapse of time or both) a default under any indenture, agreement or
other instrument referred to in clause (iii)(A)(3) of this Section 2.1(c);

          (d) No Default or Event of Default.   As of the date hereof and after
              -------------------------------                                  
giving effect to this Amendment, no Default or Event of Default has occurred
which is continuing; and

          (e) All Other Representations and Warranties.   All the
              ----------------------------------------           
representations and warranties contained in Section VI of the Credit Agreement
are true and correct in all materials respects with the same force and effect as
if made by the Company on and as of the date hereof (except as to the extent
that any such representations or warranties relate to a specific prior date or
period).

SECTION 4. CONDITIONS TO EFFECTIVENESS OF THIS AMENDMENT.

      4.1  Effective Date.  This Amendment shall not become effective until, and
           --------------                                                       
shall become effective when, each and every one of the following conditions
shall have been satisfied or waived by the Agent, the Issuing Bank and the
Required Banks (the "Effective Date"); provided, however, that the provisions of
                     --------------    --------  -------                        
Section 2.1 of this Amendment, to the extent such provisions add or change
definitions of terms used in the Credit Agreement as amended by this Amendment
(other than with respect to the definition of "Restricted Payment"), shall
become effective as of the date on which each of the following conditions (other
than clause (c)) shall have been satisfied or waived by the Agent, the Issuing
Bank and the Required Banks.

                                      -7-
<PAGE>
 
          (a) Execution of Counterparts.  Counterparts of this Amendment shall
              -------------------------                                       
have been executed and delivered by each of the Company, the Guarantors, the
Agent, the Issuing Bank and the Banks.

          (b) Representations True; No Event of Default.   The Company shall
              -----------------------------------------                     
have delivered to the Agent an Officer's Certificate, dated the Effective Date,
certifying that the representations and warranties of the Company contained
herein shall be true on and as of the Effective Date (except as to the extent
that any such representations or warranties relate to a specific prior date or
period) and that there exists no Event of Default or Default, assuming for this
purpose that this Amendment had been effective from and after the date hereof.

          (c) Consummation of Stock Repurchase.  Concurrently with or
              ---------------------------------                      
immediately after the consummation of the transactions hereunder and in any
event not later than March 30, 1998, the Stock Repurchase shall have been
consummated in accordance with all applicable statutes, laws, rules and
regulations.

          (d) No Material Adverse Change.  There shall have been no material
              ---------------------------                                   
adverse change in the business, earnings, prospects, properties or condition
(financial or otherwise) of the Company or any of its Subsidiaries since
December 31, 1997.

          (e) Fees and Disbursements of Special Counsel for the Agent.  The
              --------------------------------------------------------     
Agent's special counsel, Paul, Hastings, Janofsky & Walker LLP ("Special
                                                                 -------
Counsel"), shall have received payment of the invoice rendered for its fees and
-------
disbursements posted through the date of such invoice (with the understanding
that a supplemental statement for fees and disbursements subsequently posted is
to be rendered at a later date) in connection with the consummation of the
transactions contemplated hereunder.

          (f) Amendment Fee.  The Company shall pay to the Agent for the account
              -------------                                                     
of each Bank , which (i) indicates its approval to this Amendment by executing a
copy of the letter from the Agent to each Bank dated January 16, 1998 and
returning such letter by telecopy to the Agent by no later than 5:00 p.m. (Los
Angeles time) on January 21, 1998 and (ii) executes a counterpart of this
Amendment, an amendment fee equal to one-eighth of one percent (1/8%) of such
Bank's Commitment, and such amendment fee shall be due and payable on the
Effective Date whether or not the Stock Repurchase has been or will be
consummated.

          (g) Consents.  The Company shall have delivered to the Agent an
              ---------                                                  
Officer's Certificate, dated the Effective Date, certifying that any necessary
consents, 

                                      -8-
<PAGE>
 
waivers, approvals, authorizations, registrations, filings and notifications in
connection with the authorization, execution and delivery of this Amendment have
been obtained or made and are in full force and effect.

          (h) Proceedings, Instruments, etc.  All proceedings and actions taken
              ------------------------------                                   
on or prior to the Effective Date in connection with the transactions
contemplated by this Amendment and all instruments incident thereto shall be in
form and substance satisfactory to the Agent and its Special Counsel, and the
Agent and its Special Counsel shall have received copies of all documents that
it or they may request in connection with such proceedings, actions and
transactions (including, without limitation, copies of court documents,
certifications, and evidence of the correctness of the representations and
warranties contained herein and certifications and evidence of the compliance
with the terms and the fulfillment of the conditions of this Amendment) in the
form and substance satisfactory to the Agent and its Special Counsel.

SECTION 5. PAYMENT OF AGENT'S COUNSEL FEES AND EXPENSES.

      5.1  The Company agrees to pay upon demand, the reasonable fees and
expenses of Paul, Hastings, Janofsky & Walker, LLP, counsel to the Agent, in
connection with the negotiation, preparation, approval, execution and delivery
of this Amendment.

SECTION 6. CONSENT OF GUARANTORS.

      6.1  Each Guarantor, as a guarantor under the Credit Agreement, hereby
consents to the terms of this Amendment and hereby confirms and agrees that its
Guaranty is, and shall continue to be, in full force and effect and is hereby
ratified and confirmed in all respects.

SECTION 7. CONSENT OF AGENT AND BANKS.

      7.1  Pursuant to Section 11.01 of the Credit Agreement, each of the Agent,
the Issuing Bank and the Banks hereby consents to the Stock Repurchase by the
Company.

SECTION 8. MISCELLANEOUS.

      8.1  Cross-References.  References in this Amendment to any Section are,
           -----------------                                                  
unless otherwise specified, to such Section of this Amendment.

                                      -9-
<PAGE>
 
     8.2  Instrument Pursuant to Existing Credit Agreement;
          -------------------------------------------------

          Limited Amendment.  This Amendment is executed pursuant to Section
          ------------------                                                
11.01 of the Credit Agreement and shall (unless otherwise expressly indicated
herein) be construed, administered, and applied in accordance with all of the
terms and provisions of the Credit Agreement, including Section 11.01 thereof.
Except as expressly amended, any conditions of the Credit Agreement shall remain
unamended and unwaived.  The amendments set forth herein shall be limited
precisely as provided for herein to the provisions expressly amended herein and
shall not be deemed to be a waiver of, amendment of, consent to or modification
of any other term or provision of any other document or of any transaction or
further action on the part of the Company or the Guarantors which would require
the consent of any Bank, the Issuing Bank or the Agent under the Credit
Agreement.

     8.3. Successors and Assigns.  This Amendment shall be binding upon and
          -----------------------                                          
inure to the benefit of the parties hereto and their respective successors and
assigns.

     8.4  Counterparts.  This Amendment may be executed simultaneously in two or
          -------------                                                         
more counterparts, each of which shall be deemed to be an original but all of
which shall constitute together but one and the same instrument.

     8.5  Governing Law.  This Amendment and the notes shall be governed by and
          --------------                                                       
construed in accordance with the laws of the State of California.

                                      -10-
<PAGE>
 
          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be duly executed and delivered by their proper and duly authorized officers as
of the day and year first above written.


                                   CB COMMERCIAL REAL ESTATE 
                                   SERVICES GROUP, INC.


                                   By: /s/ John C. Haeckel
                                      ------------------------------------
                                   Name:   John C. Haeckel
                                   Title:  Senior Executive Vice President,
                                           Chief Financial Officer


                                   BANK OF AMERICA NATIONAL TRUST
                                   AND SAVINGS ASSOCIATION,
                                   as Agent



                                   By: /s/ Janet Hammond
                                      -------------------------------------
                                   Name:   Janet Hammond
                                   Title:  Vice President
                                           Agency Specialist

                                      -11-
<PAGE>
 
                           BANK OF AMERICA NATIONAL TRUST    
                           AND SAVINGS ASSOCIATION, as
                           Issuing Bank


                           By: /s/  Gina M. West
                              --------------------------------------------
                               Name:  Gina M. West
                               Title: Vice President



                           BANK OF AMERICA NATIONAL TRUST         
                           AND SAVINGS ASSOCIATION, as a Bank


                           By: /s/  Gina M. West
                              --------------------------------------------
                               Name:  Gina M. West
                               Title: Vice President


                           THE SUMITOMO BANK, LIMITED


                           By: /s/  Goro Hirai
                              --------------------------------------------
                               Name:  Goro Hirai
                               Title: Joint General Manger


                           WELLS FARGO BANK, N.A.


                           By: /s/  Clare T. Gurbach
                              --------------------------------------------
                               Name:  Clare T. Gurbach
                               Title: Vice President
 

                                      -12-
<PAGE>
 
                           BHF-BANK AKTIENGESELLSCHAFT

                           By: /s/  Dan Dobrjanskyj
                              --------------------------------------------
                               Name:  Dan Dobrjanskyj
                               Title: Assistant Vice President

                           By: /s/  Anthony Heyman
                              --------------------------------------------
                               Name:  Anthony Heyman
                               Title: Assistant Treasurer


                           CREDIT LYONNAIS LOS ANGELES          
                           BRANCH


                           By:  /s/ Diane M. Scott
                              --------------------------------------------
                               Name:  Diane M. Scott
                               Title: Vice President and Manager

 

                           DRESDNER BANK AG, NEW YORK 
                           BRANCH AND GRAND CAYMAN BRANCH

                           By: /s/  Christopher E. Sarisky
                              --------------------------------------------
                               Name:  Christopher E. Sarisky
                               Title: Assistant Treasurer

                           By: /s/  John W. Sweeney
                              --------------------------------------------
                               Name:  John W. Sweeney
                               Title: Assistant Vice President


                           KEY BANK NATIONAL ASSOCIATION


                           By: /s/  Richard J. Ameny. Jr.
                              --------------------------------------------
                               Name:  Richard J. Ameny. Jr.
                               Title: Assistant Vice President

                                      -13-
<PAGE>
 
                           THE BANK OF NOVA SCOTIA


                           By: /s/  M. Van Otterloo
                              --------------------------------------------
                               Name:  M. Van Otterloo
                               Title: Senior Relationship Manager



                           LASALLE NATIONAL BANK


                           By: /s/  John Berghorst
                              --------------------------------------------
                               Name:  John Berghorst
                               Title: Vice President

 

                           THE MITSUBISHI TRUST AND BANKING
                           CORPORATION


                           By: /s/  Yasushi Satomi
                              --------------------------------------------
                               Name:  Yasushi Satomi
                               Title: Senior Vice President



                           THE SAKURA BANK, LIMITED

                           By: /s/  Fernando Buesa
                              --------------------------------------------
                               Name:  Fernando Buesa
                               Title: Vice President

                           By: /s/  Ofusa Sato
                              --------------------------------------------
                              Name:   Ofusa Sato
                              Title:  Senior Vice President and Assistant
                                      General Manager

                                      -14-
<PAGE>
 
                           THE BANK OF NEW YORK


                           By: /s/  Jonathan Rollins
                              --------------------------------------------
                               Name:  Jonathan Rollins
                               Title: Assistant Vice President



                           MELLON BANK, N.A.


                           By: /s/  L.C. Ivey
                              --------------------------------------------
                               Name:  L.C. Ivey
                               Title: Vice President



                           THE FUJI BANK, LIMITED, LOS ANGELES 
                           AGENCY


                           By: /s/  Masahito Fukuda
                              --------------------------------------------
                               Name:  Masahito Fukuda
                               Title: Joint General Manager



                           NATEXIS BANQUE-BFCE


                           By:      Not a signatory
                              --------------------------------------------
                               Name:
                               Title:

                                      -15-
<PAGE>
 
                           BANK OF MONTREAL


                           By: /s/  B.A. Blucher
                              --------------------------------------------
                               Name:  B.A. Blucher
                               Title: Senior Vice President

                                      -16-
<PAGE>
 
The foregoing Amendment is
consented to and accepted:



CB COMMERCIAL REAL ESTATE GROUP, INC.,
a Delaware corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Senior Executive Vice President,
           Chief Financial Officer and Treasurer




KOLL MANAGEMENT SERVICES, INC.,
a Delaware corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Senior Executive Vice President,
           Chief Financial Officer and Treasurer



WESTMARK REALTY ADVISORS LLC,
a Delaware limited liability company



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Vice President and Assistant Treasurer

                                      -17-
<PAGE>
 
L.J. MELODY & COMPANY,
a Texas corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Treasurer



CB COMMERCIAL/KOLL CORPORATE FACILITIES MANAGEMENT, INC.,
a Delaware corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Assistant Treasurer



KOLL INVESTMENT MANAGEMENT, INC.,
a California corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Vice President and Assistant Treasurer



KOLL BREN REALTY ADVISORS, INC.,
Delaware corporation


By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Senior Executive Vice President,
           Chief Financial Officer and Treasurer

                                      -18-
<PAGE>
 
CBS INVESTMENT REALTY, INC.,
an Arizona corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Senior Executive Vice President,
           Chief Financial Officer and Treasurer



KOLL PARTNERSHIPS I, INC.,
a Delaware corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Senior Executive Vice President,
           Chief Financial Officer and Treasurer



KOLL PARTNERSHIPS II, INC.,
a Delaware corporation



By: /s/ John C. Haeckel
    ---------------------------------------------
    Name:  John C. Haeckel
    Title: Senior Executive Vice President,
           Chief Financial Officer and Treasurer

                                      -19-
<PAGE>
 
KOLL/CC&F MANAGEMENT SERVICES,
a California general partnership

By: KOLL MANAGEMENT SERVICES, INC.,
    General Partner



    By: /s/ John C. Haeckel
        ---------------------------------------------
        Name:  John C. Haeckel
        Title: Senior Executive Vice President,
                Chief Financial Officer and Treasurer

                                      -20-