It's so heartbreaking not to be able to do anything about their very real troubles, isn't it? My DS8 has had lots of broken-hearted woe and tears over the years, and it doesn't get any easier to help -- and we're not in Alaska!
I think perhaps it might help if you enlist the help of the older children. Find likely candidates in that 8-ish age range and talk to them privately about your DD and how she could be a great playmate for them -- explain that she isn't like the "babies" that they probably compare her to, and ask them to try being her friend. Then turn them loose and see what happens. I think that would be easier and faster than waiting for them to notice on their own while she sits around being frustrated at being misunderstood. And they will get to feel like they are part of a secret, like they know something that other people don't.
