Synchongenic

Synchongenic is an origin term that describes a subsystem that formed due to two or more headmates partially fusing with each other. synchongenic (adj.):

History
Elysia of the Stardust Collective coined this term on November 24, 2021, putting the term onto their collective's shared Tumblr page (linked here). Xe coined it to describe xyr experiences with how xyr subsystem, the Gemini Cluster, formed.

Related Terms
Fusion is the process of two or more headmates or fragments becoming one.

Subsystems are systems within systems; often when a headmate has a system of their own.