Dear Prudence,
My sister has two children from a man in a different state who does not pay child support, mostly because she refuses to file the necessary paperwork. (She seems to equate it with giving the father some rights to see his children, whom he’s never met.) I have done everything I can short of physically dragging her to the courthouse, including contacting him myself. That is how I learned he’s getting married soon and that his fiancée knows nothing of his children. I can’t get my sister or this man to alter their behavior for the better. Do I owe it to the fiancée to out this man to her before the wedding? Child support obligations never go away, and this could come back to haunt them.
—Secret Children
Re: 4 Men in the world, and I want to control them all, as well as all my siblings
Even in this case, I wouldn't want to be involved in the situation, and would tell sister to take care of her business and ask her baby daddy.
Otherwise, LW needs to back off.