No way should maintenance be paid to the parent once the child is an adult. Either support the child directly or stop the money.
My oldest is 19, at university. She lives away from home. I still pay for her mobile phone bill and I have just helped with buying her a car as her old one failed it's MOT so badly it is only fit for the scrapheap.
It's my choice to do that. She doesn't expect it. Her dad stopped paying maintenance when she was 16 despite her being in full time education until 18.
We are in danger of having a generation of adults who expect their parents to pay for everything and do everything for them, despite them being adults themselves.
Yes, help them out if they are stuck (she needs a car, so I helped her, I paid half) but on a day to day basis I expect her to budget her loan, make sure she has sufficient money put away to pay for accommodation and her car insurance renewal and it's really only dire emergencies that I stick my hand in my pocket.
Sounds harsh but when I hear some of the stuff she tells me about girls in her Halls who are third year students and their parents are still paying for everything, including all their food and they have no idea how to cook the bloody food, I wonder who is doing things right.