Polymultiple

undefined: Polymultiple systems have a large amount of partitionary members.

The "multiple" used here does not refer to the large plural umbrella but to the specific experience of having distinct headmates, as compared to median & OSDD-1a systems.

Related Terms
Polyplural refers to any large system, whether they are partitionary or not; in addition, polyfaceted & polyfragmented describe similar phenomena.

DID is a common example of a partitionary or multiple system.