So I figured I'd update this thread.
After quite a bit of thought and discussion with my hubby, we decided on this little girl.
Meet Daisy. After meeting her I just couldn't leave her where she was. She's a rescue dog. 2.5 years old, VERY fearful of people and a biter. She's bitten me 3 times now but it's not her fault. Plus I've been bit by bigger dogs than her before. She's terrified, was obviously abused.
I had to have her clipped short. Her coat was completely matted to the skin. It'll grow out though. She's 4 lbs and the vet said she's healthy. I just had her spayed and she's recovering nicely. Gotta love laser surgery.
The important thing is she gets along beautifully with Gabby. She doens't have issues with other dogs, just people. It's going to take some time to teach her that not all hands are there to hurt you.