I would say that you should be able to do a number of different things:
1. have her refinance the old house, but that would give you a higher rate.
2. Have her refinance her new house with a HELOC on the new house to pay off the debt on the old house. Then you just take over the property. No payments on the equity, because she already has the equity. Well, maybe pay her something when it sells.
3. She if she can convert the bridge loan into something. Many times there exists the option to do so, for these type situations