I need to fix a family

I have a household that I have been playing for a while that includes 2 siblings and one of the siblings partners. Through some unforeseen turn of events, the partner became siblings with the siblings and I can't figure out how to change it. I have tried removing the relationship bits with MCCC, clearing the relationships, and editing the household from the library in CAS. No matter what I do the relationship stays in the genealogy of the sims and affects how they interact with each other. Is there anything I can do?