Have NC as this is totally outing. Just curious really. My father is a grade A arsehole currently on wife #5 and I have several half siblings, including some very young ones he had with wife #4 (I don't doubt there will be more!).
I have a very fractious relationship with the sibling of the marriage directly before my DM's with my father, as in their eyes I and my one full sibling had a much better life and more attention from my father than they did (I don't agree!!) but am relatively close to the others. It's left me with a total aversion to the notion of a blended family though. I dread the mess that will be left when my Dad dies. God knows what extra skeletons he has in the closet.