Once read where a guy married a women with 2 children, he adopted them, then the woman left leaving him responsible for raising the children.
I met a guy who had married a widowed young mother with two children - she was pregnant with one and the other was a toddler. He adopted them both but she never let him have any say in any of the child raising decisions. (I figured he was basically a paycheck, free room and board for her and her kids.) Then she left him when the youngest turned 18. Oh well...
It’s very common in the military. A woman with kids marries an active servicemember. She convinces him to adopt her kids. Once the adoption is complete, she divorces and then demands support payments. Each kid gets an ID so the woman has base access and kids rate exchange and commissary privileges.