He's barging and rough now at 6 months. In a year's time he will be dangerous, especially to your M-i-L, so either he needs to go for slaughter or, as I suspect you would prefer, go out with the flock. If you are seriously concerned about his being bullied out there, put him with another wether, or his mum, in a pen for a while, even his overnight shed, so he has a pal and learns what a sheep is. After a couple of days, return them both to the flock, and he will have a pal. You will just have to harden your heart until he settles in.
The best advice we had when we started with sheep was 'never have a pet lamb'. We have followed that almost totally, so any rejected lamb is adopted onto another ewe or if there's not one available, the lamb is bottle fed in the field with the flock. That way it knows it's a sheep, and it's with the flock from day 1, it's not imprinted on a human and it doesn't expect much special treatment. Baby lambs are so cute and I can see why folk love them so, but in the long term it rarely works for ever. They are sheep and they need to live in a flock.