A friend of mine was induced b/c baby was 'too big' and 'at least' 9-10 lbs. Induction turned into failure to progress, turned into c-section, for a baby that was about 7 1/2 lbs. (Oh, it turned out to be a great thing b/c her ds had cord around his neck, which from what I understand is pretty normal and not a reason for a c-sec.)
That is the basic story time and again, but if she wants to schedule, there's really nothing you can do about it. People can look large for many reasons, not just b/c of a large baby and u/s are only accurate +/- 1-2 lbs, if I remember correctly. 1-2 lbs on a newborn is a HUGE difference.
Maybe you could point her in the direction of some resources to review, but if she's trusting her doc, she's trusting her doc and probably won't switch this late in the game unless she really feels something is wrong. That doesn't sound like the case here.