Re: [ARCHIVED] Partnered Sims turn into siblings/family relationships

The same happened to me and it was really annoying. I believe the reason why it happens is some sort of bug with CAS.fulleditmode which I use a lot. I found a fix for it (after many hours of despair) and you need the MCC mod, because any other cheats won't work - at least they didn't for me. 

With MCC, click on one of the sims you want to change the relationship and search for the tab "relationships" (if it doesn't show up on the first page, select next).

Then you'll have to delete ALL relationships that the chosen sim has with EVERYONE else. There's the option to "forget" too, but it won't work. So look for "clean relationships" or something like this. 

Now they won't have any relationships with anyone - including family members. All you need to do is add relationships with family members. 

It's going to be really tiring to get all your friends back (even with MCC), but at least that horrible bug is fixed. It's working perfectly for me so far.

I am having this problem as well. Any help is GREATLY appreciated. I took out all mods and deleted localthumbcache, bug is still there.

This has just happened with me as well, and I think you're on to something with the clone thing, because my sims are spellcasters and one of the them created a duplicate of herself using magic, and now when I look at her family tree...

See, the sim who created the duplicate is the one in the hat, her spouse is on her right (notice that it is now redded out), and on her left is her duplicate AND another image of her wife, BOTH labeled as sisters. They're connected to a parent that never existed, as this sim was originally generated in game. Keep in mind, I can't find any actual double of the wife any where, it just seems that the game has glitched and is now counting her twice.  

I tried using MCC to delete their relationship and then restore them as spouses, but it just reverted to the having them be sisters AND spouses the next time I loaded the game. I'm seeing the suggestion to delete ALL the sim's relationships...but man, that's a pain in the you know what. Both of them have built up quite a lot of friends, enemies, and the wife has an aunt and cousin in another household. Deleting and manually restoring those would be at best a hassle, and at worst impossible. 

I dunno, this is just really annoying, and I hope someone figures out a better fix before I resort to the nuclear option. 

I actually edited their relationships with "remove relationship bit". I had to do this with my sims father in-law, wife, and children only. After that it said the children were her step-children and her wife was her cousin instead of sister, but the family tree was intact.

I had this problem too: My sim is a witch, and she made a duplicate of herself, and now I can't really use romantic interactions between her and her partner. The last time I actually could use romantic interactions was before the double was created. I am not sure how to fix this, especially without mods.

I'm having this problem too currently, but my problem started when I used MCCC to accidentally make my female vampire Sim the sister of Alexander Goth. I deleted their relationship afterwards, but it keeps putting them as brother and sister, even though they're husband and wife. And their kids keep getting changed to brother/sister/cousins. I have since deleted the relationships between my female Sim and Alexander Goth about 5 times now. I even deleted a bugged version of the female Sim and added a new version of her to the game, but she still ends up being the sister of Alexander Goth, even though she is his wife. I should also note that everyone in my household are vampires, I have never played with a spellcaster in this save, and I have not duplicated/cloned any Sims. The problem seems to exist in both the game itself and MCCC, as it started happening in my game after I accidentally made my female Sim and Alexander Goth brother and sister using MCCC. And since then, the game continuously seems to think they are brother and sister, even though they are married to one another/have children with one another.

Edit: And I only accidentally made them brother and sister using MCCC to begin with, because my female Sim would not romance Alexander Goth at all (the only option she had under romance was "Offer Massage"). I do use mods in my game, but seeing as this problem happens to people who don't even use mods, I don't think this is mod-related; I think it's a game bug and a game-breaking bug at that. EA, you need to fix this ASAP!

I tried this and it worked temporarily.

Eventually, Bella Goth became my sims mother again.

Thinking the issue was that somehow the Sim was connected to Mortimer (who is already culled)

I deleted the affected the sims, created new ones, and at some point re-establishing relationships, Bella became mom again... Not sure what the issue is.