That's sort of "meet the family" only not, isn't it? Because a lot of "meet the parents", the parents are off somewhere in the picturesque hometown, not part of daily life, whereas what you're talking about, the family the SO has to get used to is their everyday. Yeah, I can think of some stories I liked that did that, but I can't think of how I'd find something like that out of nowhere.

It's also tough because usually the codependent people *are* the main cast, so bringing a new person in usually means an OC/crossover character/AU, and those are always tricky.