29 C.F.R. § 4022B.1

(a) Benefits with respect to two or more plans. If a person (or persons) is entitled to benefits payable with respect to one participant in two or more plans, the aggregate benefits payable by PBGC from its funds is limited by § 4022.22 of this chapter (without regard to § 4022.22(a)). The PBGC will determine the limitation as of the date of the last plan termination.

(b) Benefits with respect to two or more participants. The PBGC will not aggregate the benefits payable with respect to one participant with the benefits payable with respect to any other participant (e.g., if an individual is entitled to benefits both as a participant and as the spouse of a deceased participant).