Ann,
PLEASE be sure to check your
Homeowners Insurance Policy to make sure there are not exclusions for pets of "dangerous breeds" such as, Rottweiler, Pit Bull, etc.
I commend you for taking in this Momma-Girl but, please be careful to not put your family at risk financially if the unimaginable should occur and she does act out hurting someone on your property.
In the meantime, all you can do is keep on top of the rescue groups in your area & beyond to find accommodations for her with a foster family.
As a Yorkshire Terrier foster mom myself, we're seeing the most horrible times for dumping & surrendering. You can only blame the economy so far and then the rest belongs upon the shoulders of too many uneducated & unloving pet owners.
All the best
Jo Ann