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                                                                   EXHIBIT 10.21

                    JOINDER TO REGISTRATION RIGHTS AGREEMENT

     This Joinder Agreement (this "JOINDER AGREEMENT") is made as of the date
written below by the undersigned (the "JOINING PARTY") in accordance with
Section 3.16 of the Registration Rights Agreement dated as of February 27, 2004
(the "REGISTRATION RIGHTS AGREEMENT") (as the same shall be amended,
supplemented or otherwise modified from time to time), among Solo Cup Investment
Corporation and the parties set forth on the signature pages thereto and any
other signatories added thereafter (including by the execution of a similar
joinder agreement). Capitalized terms used, but not defined, in this Joinder
Agreement shall have the meaning ascribed to those terms in the Registration
Rights Agreement.

     The Joining Party hereby acknowledges, agrees and confirms that, by its
execution of this Joinder Agreement, the Joining Party shall become a party to
the Registration Rights Agreement as of the date hereof and shall have all of
the rights and obligations of a Management Investor thereunder as if it had
executed the Registration Rights Agreement directly as a Management Investor.
The Joining Party hereby agrees to be bound as a Management Investor by all of
the terms, provisions and conditions contained in the Registration Rights
Agreement.

     IN WITNESS WHEREOF, the undersigned has executed this Joinder Agreement as
of the date written below.

     Date: __________, 2004

                                     JOINING PARTY:

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

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

Acknowledged and Accepted by:

SOLO CUP INVESTMENT CORPORATION


By:
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Name:
Title: