Yep!
I had a case similar to this one. Caretaker forged and notarized a deed from elderly employer to herself. Caretaker recorded the deed after employer died, and took out a $70K mortgage. The heirs sought to set aside the deed, and I filed a suit to quiet title based upon a clearly forged instrument. Didn’t even need a handwriting expert. Mortgage company agreed to pay off the heirs the value of the house, and kept the collateral and the right to sue the forger.
This grandma can forgive all she wants, but she’ll need to throw the granddaughter under the bus in order to strip that mortgage.