I would tend to have her look at the lab and golden crosses too.
While there are always exceptions those breeds are known for being family dogs. Most are usually very tolerant. I don't know how old the kids are though, as they can also be quite rambunctious and may be too much for really small kids (big tails whapping children in the faces, wagging bodies bowling children over).

I would also try to steer her towards an older pup or young adult. Hopefully old enough to have grown out of most of the more annoying puppy traits, yet young enough to be really playful.

Good luck in finding Jake a great home with someone who will understand his breed better. And good luck with helping your sis find the right dog so that this doesn't happen again.