Document:

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                                                                   EXHIBIT (10a)

                                SECOND AMENDMENT
                                       TO
                           MANAGEMENT PERFORMANCE PLAN
                               OF USG CORPORATION

     SECOND AMENDMENT (this "Second Amendment"), to the Omnibus Management
Performance Plan of USG Corporation originally approved by the stockholders of
the Corporation on July 8, 1988, and amended on November 15, 1994 (collectively,
the "Plan").

WHEREAS, the Compensation and Organization Committee of the Board of Directors
of USG Corporation (the "Corporation") has approved an amendment to the Plan to
impose additional conditions on certain awards under the Plan;

NOW, THEREFORE, in consideration of the premises, the Plan is hereby amended as
set forth below:

1.   The Plan is hereby amended by the addition of a new Section 6(f)
     consisting of two (2) sentences to read as follows:

         "In the event the Committee permits the surrender of previously-owned
         shares of Common Stock as payment for the exercise price of any award
         under the Plan, such shares shall have been beneficially owned by the
         grantee for not less than six (6) months and otherwise qualify as
         "mature" shares under Generally Accepted Accounting Principles. In the
         event the Committee permits the reduction of shares of Common Stock
         subject to any award under the Plan in order to satisfy tax
         withholding, such reduction may not exceed the then statutorily
         required rate of withholding."

2.   Except as expressly amended and modified by this Second Amendment, the
     Plan is hereby ratified and confirmed in all respects.

     IN WITNESS WHEREOF, the Corporation has caused this Second Amendment to be
executed by its officers thereunto duly authorized as of the 27th day of June,
2000

                                        USG CORPORATION

                                        By /s/ Peter K. Maitland
                                           ---------------------------
                                               Peter K. Maitland
                                               Vice President, Compensation,
                                               Benefits and Administration

Attest:

/s/ Dean H. Goossen
-------------------------
Dean H. Goossen
Corporate Secretary<PAGE>   1
                                                                   EXHIBIT (10b)

                                 FIRST AMENDMENT
                                     TO THE
                           1995 LONG-TERM EQUITY PLAN
                               OF USG CORPORATION

     FIRST AMENDMENT (this "First Amendment"), to the 1995 Long-term Equity Plan
of USG Corporation originally approved by the stockholders of the Corporation on
May 10, 1995 (the "Plan").

WHEREAS, the Compensation and Organization Committee of the Board of Directors
of USG Corporation (the "Corporation") has approved an amendment to the Plan to
impose additional conditions on certain awards under the Plan;

NOW, THEREFORE, in consideration of the premises, the Plan is hereby amended as
set forth below:

1.   Section 8(e) of the Plan is hereby amended by the addition of the following
     two (2) sentences at the end thereof:

          "In the event the Committee permits the surrender of previously-owned
          shares of Common Stock as payment for the exercise price of any award
          under the Plan, such shares shall have been beneficially owned by the
          grantee for not less than six (6) months and otherwise qualify as
          "mature" shares under Generally Accepted Accounting Principles. In the
          event the Committee permits the reduction of shares of Common Stock
          subject to any award under the Plan in order to satisfy tax
          withholding, such reduction may not exceed the then statutorily
          required rate of withholding."

2.   Except as expressly amended and modified by this First Amendment, the Plan
     is hereby ratified and confirmed in all respects.

     IN WITNESS WHEREOF, the Corporation has caused this First Amendment to be
executed by its officers thereunto duly authorized as of the 27th day of June,
2000

                                   USG CORPORATION

                                   By /s/ Peter K. Maitland
                                      --------------------------
                                          Peter K. Maitland
                                          Vice President, Compensation,
                                          Benefits and Administration

Attest:

/s/ Dean H. Goossen
-------------------------
Dean H. Goossen
Corporate Secretary<PAGE>   1
                                                                   EXHIBIT (10c)

                                SECOND AMENDMENT
                                       TO
                        OMNIBUS MANAGEMENT INCENTIVE PLAN
                               OF USG CORPORATION

     SECOND AMENDMENT (this "Second Amendment"), to the Omnibus Management
Incentive Plan of USG Corporation originally approved by the stockholders of the
Corporation on May 14, 1997, and amended on November 11, 1997 (collectively, the
"Plan").

WHEREAS, the stockholders approved an amendment to the Plan on May 10, 2000, to
increase the number of shares reserved for issuance thereunder; and

WHEREAS, the Compensation and Organization Committee of the Board of Directors
of USG Corporation (the "Corporation") has approved an amendment to the Plan to
impose additional conditions on certain awards under the Plan;

NOW, THEREFORE, in consideration of the premises, the Plan is hereby amended as
set forth below:

1.   Section 6 of the Plan is hereby amended in its entirety to read as follows:

        "The number of shares of Common Stock reserved for issuance under the
        Plan after December 31, 2000, through December 31, 2003, is 2,400,000,
        together with such shares that are unissued or are the subject of
        forefeitures of any award under the Plan or any predecessor long-term
        incentive plan, which shall thereupon become available for awards
        under the Plan."

2.   Section 5(a) (iv) of the Plan is hereby amended by the addition of the
     following sentence at the end thereof:

        "Notwithstanding anything in this Plan to the contrary, awards of
        Common Stock that are performance-based shall have performance periods
        of not less than one(1) year."

3.   Section 11(c) of the Plan is hereby amended by the addition of the
     following two (2) sentences at the end thereof:

        "In the event the Committee permits the surrender of previously-owned
        shares of Common Stock as payment for the exercise price of any award
        under the Plan, such shares shall have been beneficially owned by the
        grantee for not less than six (6) months and otherwise qualify as
        "mature" shares under Generally Accepted Accounting Principles. In the
        event the Committee permits the reduction of shares of Common Stock
        subject to any award under the Plan in order to satisfy tax
        withholding, such reduction may not exceed the then statutorily
        required rate of withholding."

4.   Except as expressly amended and modified by this Second Amendment, the
     Plan is hereby ratified and confirmed in all respects.

<PAGE>   2
     IN WITNESS WHEREOF, the Corporation has caused this Second Amendment to be
executed by its officers thereunto duly authorized as of the 27th day of June,
2000

                                          USG CORPORATION

                                          By  /s/ Peter K. Maitland
                                            -------------------------
                                                  Peter K. Maitland
                                                  Vice President, Compensation,
                                                  Benefits and Administration

Attest:

/s/  Dean H. Goossen
----------------------------
Dean H. Goossen
Corporate SecretaryEXHIBIT 4.1

                          SUPPLEMENTAL INDENTURE NO. 1

                          dated as of October 25, 2000

                                      among

                             TRIARC COMPANIES, INC.,

                        SBG HOLDINGS INC., as Successor,

                                       and

                              THE BANK OF NEW YORK,
                                   as Trustee

                           --------------------------

            Zero Coupon Convertible Subordinated Debentures Due 2018

<PAGE>

                  THIS SUPPLEMENTAL INDENTURE No. 1 (this "Supplemental
Indenture"), dated as of October 25, 2000, among TRIARC COMPANIES, INC., a
Delaware corporation (the "Company"), SBG HOLDINGS INC., a Delaware corporation
(the "Successor"), and THE BANK OF NEW YORK, as Trustee (the "Trustee").

                                    RECITALS

                  WHEREAS, the Company and the Trustee entered into the
Indenture, dated as of February 9, 1998 (as amended, supplemented or otherwise
modified from time to time, the "Indenture"), relating to the Company's Zero
Coupon Convertible Subordinated Debentures Due 2018 (the "Securities");

                  WHEREAS, pursuant to the Agreement and Plan of Merger, dated
as of September 15, 2000 (the "Merger Agreement"), by and among Cadbury
Schweppes plc, CSN Acquisition Inc., CRC Acquisition Inc., the Company, Snapple
Beverage Group, Inc., and Royal Crown Company, Inc., the Company is conveying
and transferring, and the Successor is acquiring, the properties and assets of
the Company substantially as an entirety (the "Transaction");

                  WHEREAS, Section 5.01 of the Indenture provides that a Person
which acquires by conveyance or transfer the properties and assets of the
Company substantially as an entirety (A) shall be a corporation, limited
liability company, partnership or trust organized and validly existing under the
laws of the United States or any state thereof or the District of Columbia and
(B) shall expressly assume, by an indenture supplemental to the Indenture,
executed and delivered to the Trustee, in form satisfactory to the Trustee, the
due and punctual payment of the principal of and interest on the Securities
according to their tenor and the due and punctual performance of all of the
covenants and obligations of the Company under the Securities and the Indenture,
including the obligation to deliver shares of common stock of the Company upon
conversion of the Securities;

                  WHEREAS, Section 5.01 of the Indenture further provides that
the successor Person to which such conveyance or transfer is made shall succeed
to, and be substituted for, the Company, and may exercise every right and power
of the Company under the Indenture with the same effect as if such successor had
been named as the Company therein; and thereafter the Company shall be
discharged from all obligations and covenants under the Securities and the
Indenture;

                  WHEREAS, pursuant to the terms and conditions of Section 5.01
and Section 9.06 of the Indenture, the Trustee is authorized to sign this
Supplemental Indenture to evidence the assumption by the Successor of the
Company's obligations under the Securities and the Indenture and the release of
the Company from its obligations under the Securities and the Indenture.

<PAGE>

                                                                               2

                                    AGREEMENT

                  NOW, THEREFORE, in consideration of the premises and mutual
covenants herein contained and intending to be legally bound, the parties hereto
hereby agree as follows:

                  Section 1. Capitalized terms used herein and not otherwise
defined herein are used as defined in the Indenture.

                  Section 2. The Successor, by its execution of this
Supplemental Indenture, hereby assumes all the obligations of the Company under
the Securities and the Indenture and agrees to be bound by the terms of the
Securities and the Indenture applicable to the Company, effective upon the
completion of the Transaction.

                  Section 3. The Company is discharged from all obligations and
covenants under the Securities and the Indenture, in accordance with Section
5.01 of the Indenture.

                  Section 4. THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO
ITS PRINCIPLES OF CONFLICTS OF LAW SHALL GOVERN THIS SUPPLEMENTAL INDENTURE.

                  Section 5. The form of Conversion Notice appended to the
Securities is amended in its entirety to read as set forth on Exhibit A hereto.

                  Section 6. The recitals herein contained are made by the
Company and the Successor, and the Trustee assumes no responsibility for the
correctness thereof.

                  Section 7. This Supplemental Indenture may be signed in
various counterparts which together shall constitute one and the same
instrument.

                  Section 8. This Supplemental Indenture is an amendment
supplemental to the Indenture and said Indenture and this Supplemental Indenture
shall henceforth be read together.

<PAGE>

                                                                               3

                  IN WITNESS WHEREOF, the parties have duly executed and
delivered this Supplemental Indenture or have caused this Supplemental Indenture
to be duly executed on their respective behalf by their respective officers
thereunder duly authorized, as of the day and year first above written.

                                   TRIARC COMPANIES, INC.

                                   By:  /s/ John L. Barnes, Jr.
                                        ---------------------------------------
                                        Name:  John L. Barnes, Jr.
                                        Title: Executive Vice President

                                   SBG HOLDINGS INC.

                                   By:  /s/ Bruce Futterer
                                        ---------------------------------------
                                        Name:  Bruce Futterer
                                        Title: Treasurer and Secretary

                                   THE BANK OF NEW YORK, as Trustee

                                   By:  /s/ Julie Salovitch-Miller
                                        ---------------------------------------
                                        Name:  Julie Salovitch-Miller
                                        Title: Vice President

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