Gently slide the left-hand stem under her hair. It takes effort, but if you do it slowly, it should be fine. Push until the stub on the right side touches her hair. In that position, there shouldn't be any undo pressure on the glasses. Best I can tell, the only real tension will be her hair on the left stem, which doesn't seem to be a problem.
Hope that helps.
Thanks, I'll have to give it a shot. And yeah, she's a blast to pose, I just need one to settle on.