How to make parents for adult sim and edit relationships

So then, creating parents to existing siblings is a little glitchy...

If you create siblings with no parents and then edit them in Manage Worlds, you can create only one parent for them. The reason might be that a "hidden parent" is created so the sibling relationship would be there, but I am not an expert in this.

At least that's how I understand the problem here...

I can only recommend here to try out cas.fulleditmode, but I don't know if it works or will it go ahead and switch the parent... Worth a try I guess...