I’m not an expert. I watched my ex make everything regarding our kids about herself. I dated a stepmom who had similar issues in her relationship with her ex. I’ve seen other family members deal with similar bullshit–using the kids as a way to exact revenge, fucking with schedules/call routines, just whatever petty bullshit can be used to get back at the other person. The parents who are big enough to actually put the kids first are about as common as good, well-balanced people are otherwise, in my experience. So, not very common, at all.