I can see you reported my post to the moderator (me).
You may not like it, but its the reality. Her CS is none of your business and is between them. Nothing to do with you or your kids. If you really have an issue with it and are concerned he doesn't have enough money for his other kids that you accepted he had when the two of yoi got together, then maybe you should offer to reduce or end the CS you receive and make a new agreement. That's the extent of what your involvement should be, if anything. If you aren't willing to do that then leave her and her kids alone and mind your own business.