can a lein on a property be proven to be fraudulent?

i am named on a property with a family member through a quit claim deed recorded with the county. that same person that put me on the deed does not want me on the deed any longer ( she regrets doing it after 3 years). she claims to have made a loan from another family member with this property as the collateral (before i was put on the deed). there transaction was private and not recorded. she says that she has not paid back the loan and now must give the property up as it was collateral. i know this loan really never happened, but how do i prove it?