Problem teenagers who are unmanageable by parents; if they had a better alternative the parents would not spend their inheritance trying to save/fux them.
One of my cousins was involved in such a situation: adopted a kid of about 12 years age (don’t recall exactly), who turned out to be a very pathological individual. They had to have him involuntarily “committed” a couple of times, and when he turned 18 they had to cut all ties with him. He was abusive, manipulative, dishonest, destructive, all in all a real mess.