Revoking a TEFRA 242(b) election

[TPATC]

A participant with a TEFRA 242(b) deferral election has died with a substantial deferred MRD balance.  He is currently in the middle of a fixed 30 year installment schedule.  (Died after RBD.)  If Spouse beneficiary revokes the installment schedule, this will revoke the 242(b) election.

Question is:  Is Spouse then required to take the make-up MRD distributions of the participant within 2 taxable years, or do the make-up MRD distributions ONLY apply to the MRDs that the BENEFICIARY has deferred AFTER the participant's death?

ERISA Outline Book indicates only the post-death MRDs would have to be made up, but I have not found a supporting reference for this.

Thanks!