For the short term, I would accept jennifert9's offer of a larger
crate. That would make the dog more comfortable.It does
sound like Jade needs more training & one on one time. If you
could spend a few days a week working with her that would be great. One of the saddest parts of dogs being dumped off at
Humane Societies, is no one has ever made any efffort to train
them at all & the shelter's are not set up to do it either. It really
cheats the dog of ever finding a good home. Not many people
want to train an older dog when they can get a smaller pup.

Poor Jade is missing out on so much. Your sister is as well, but
maybe she doesn't see that.