Buyer paid in Full; Pledged to 3rd Party by seller thereafter; Seller died

My mother paid in full the parcel of land with "Deed of Absolute Sale(notarized)" and "Technical Description". The original land area was around 3k sq mtrs. This was divided into several parcel and my mom bought 200 sq. mtrs. When we're about to transfer the title, we learned that mother title was pledged to 3rd party as collateral after the buyers including my mom have paid the said property. What rights does my mother have? Right now we're unsure if property taxes are being paid and as much we would like to, we cant just yet, am i right? We talked with the geodetic engr but been informed theyre waiting for amicable settlement. Is that possible even if the rest of the buyers already filed a case in court against the third party who has the mother title. The heirs of the seller are incapable of paying the 3rd party annd taxes. No property at all. Without proper source of income. What legal actions do we need to take against the 3rd party? Coz as far as i know when part of the land has been sold without transfer of title, lien annotation is in the back portion of the title, correct? Please advise course of action we need to take.