OMG Holly, that's awful. It must be so tough for you!
It's even sad to hear that your DH was 'sucked' in to doing what he didn't want too
I'm totally for supporting your kids in their endeavours. But I reckon it takes a really special kid to have that much drive, KWIM? I think any sport (or music!) at an elite level needs a level of discipline that would be an unusual trait for a kid to have and develop all by themself.
In the case of your BIL, Holly, I'd have to say that there's no way I could stand in my kid's way if she were that focussed. I think his story is exceptional! (And *wow* to having a possible football star in your immediate family!!!)
Part of me is very much equality-based, probably due to my mum's attitude about raising kids. She has always been very careful to give us all equal everything (that's including time - like babysitting, LOL!) and I'd like to do the same for my kids. If DD was to become a child prodigy and be given an opportunity to extend it further, I'd have to make sure my other kid was aware that we want to give them the same opportunities wherever possible. I doubt we'll have one child prodigy in our house, let alone two, but even if there were one, I'd want to keep the lines of communication open between us and the non-prodigy to make sure they know they are equally valued... Does that make any sense at all?