If she could be doing all kinds of higher work and she is currently bored have you considered full grade rather than single subject acceleration? I know it's a big idea but we actually found it more successful than SSA as it avoided the issues of juggling timetable clashes and missing fun subjects. It might be worth considering if your school is already being flexible enough to consider SSA. A trial for a few weeks would give everyone the opportunity to see if it might work?
It certainly easier than relocating, which still may happen, but might give you breathing space and a better idea of what works for your DD and what her needs are.
