The ChangeMan DS Web/Java client should not allow for approvals of a linked package. This should be performed by ECP. If you create a ZMF package and link it to a DS package and approve the package in DS, you will receive an error message saying that "Approval of this package is allowed from ChangeMan ECP only". ECP does not change states from FRZ to APR, it only does approvals at the FRZ state.
