That's good that you're not blended anymore.
From what I can tell the IFS model explains the roles of different parts... and in DID the major difference is the level of dissociation between them. I am sure there is more to it though and that the parts are relationships (and non-relationships) between them are heaps more complex in DID.
Still the basic roles and functions would kind of be the same.

We have a teenage alter that gets triggered into suicidal intention. She goes through the motions of "preparing" which seems to calm the whole system down. Looking at that through the IFS lens I see her behavior, her "script" as a fire fighter part to protect against exiles for sure. I think I see the dissociative system functioning the same as internal family system with the roles and functions very similar, just with amnesia and dissociation between them.