I'll say right upfront that I'm not a fan of IFS in general. While I think it's an interesting and valid concept in theory, I don't think it's always helpful applied to all clients. The problem that IFS creates, in a way, is this very sense of separate parts that are independent of each other. Nominally, they're all parts of the adult self, but in application, the effect is to separate them, including accepting them as separate.

Because their feelings are strong and seem to touch some unmet needs your adult self has, they persist. I'm not sure "accepting" them as is leads to their lessening. I suspect their needs need to be accepted and assigned their appropriate role by the adult self for the system to be functional.