You're gonna have to talk with the secretary and find the right kid. A lot of the little girls have no tact, and it sounds like tact is what will be needed!
Probably somebody tried to muscle her somewhere along the line without taking the trouble to find out what she was thinking . . . . happens a lot, unfortunately.
And I think that's where it all falls apart. If I'm contacting them with a motive like "Hi, I have this fairly dangerous little pony, I'm looking for a kid to put on her" it's a pretty hard sell. I don't want to understate that she has definitely not thrown her last rider.
I think if I was inside that circle, I'd find the right person, but a stranger with a bad pony? Most of the instructors would be a little leery of us both.
Oh well, once in awhile I get a bee in my bonnet to do something with her... there's numerous good young eventers who gushed about her on the horse forum thread I posted about her (If a tree falls in the forest... will my pony jump it?), a few of which are probably good enough, they just aren't on the right side of the country. Maybe one of these times I'll get lucky and one of them will be close enough to say "Take her" "Try her!" please!! Just give her back if she doesn't work out". I do NOT want her sold, I don't want her ending up in the wrong place.
What might be best is a small adult who would be willing to start her. Little girls often don’t have patience with scared ponies.