I think your right that S17 will work it out but he will test as much as he can. I got away in my teenage years by setting my bar pretty low (if i put no effort in i had an excuse for failing) so that may be what S17 is doing. S17 is fortunate enough that he has a mum who is actually interested in his wellbeing.
As for H, it does sound like working through your lawyer is going to be a sensible plan if only for the stability that will provide. difficult to spew through a through a third party that is paid to protect your interests.
Both mid 30s, 2 young kids BD 7sep14 XW moved on long ago, now living with OM1 D paperwork in progress
