My brother has a son who is 17 and is working part time and at college part time. His ex is demanding money as my brother is just going back to work after being on the sick after an accident at work and breaking a bone in his neck and not being able to work for around 20 months now. He’s googled it and can’t find much out and it seams a bit complicated and never mentions the child working and what would happen in those circumstances. Does anyone know ?