How long have you had her? What you have to remember with rescue dogs, and especially dogs that came from the pound and not from a rescue group, is that they are often psychologically damaged from what they have been through. Dogs are intelligent creatures, they're sensitive, they can't go through what some people put them through and come out unscathed.
If she has been in your home less than six months, she is going to need time. Dogs are just like people when it comes to living with other dogs. They have to work out their own little arrangement within your family structure before everyone can just settle down and be a great pet.
You also have to show her what is expected of her. She can't just be expected to automatically fit into your family. When you take a new job, do you have to be shown what your responsibilities are or do you just automatically know when you walk in the door? After all, you've had a job before, right? See where I'm going with this? It's the same thing for dogs. You can't expect them to just know what to do in your home, you've got to train them to do things the way you do them in your house.
In the long term, you can only expect to get back what you put into it. If you leave the dogs to their own devices, chances are they're only going to be able to go so far and even if they do make some progress, what THEY come up with as a solution may not work for the humans of the family. The best thing to do would be to consult a trainer and ask them what they feel would be the best way to integrate a new dog into the household. I hope Jaybay is able to get here to see this question, also, because she has some EXCELLENT training suggestions. I know she would be able to offer something for you to try.
Ghilly
How long have you had her? Rescue dogs can have a very difficult time adjusting.