I'd have to reorder it for
Radio 4
Radio 1, group
Radio 2
Radio 3
Radio 5, group
Radio 6
Radio 7
I think this would make more sense:
Radio 4, group
Radio 1, group
Radio 2
Radio 3
Radio 5, group
Radio 6
Radio 7
I guess this is just the way I do things, but I think if you use groups you should group everything.
You can group other controls but I can't see any effect it would have on them.