If he had medical bills or any credit bills, will I be sorry to try to get this in our names as the heirs?

We didn't hear of a will and filed a petition with the surrogate court as instructed by our lawyer. My dad had 3 children. I being one of them was appointed administrator of his estate. My sister and brother signed waivers and are on board with my actions. Dad owned 2 building lots in which the taxes were not being paid. When girlfriend of 30 years received letter from our attorney to remove the lots because she is not the owner, she said I have a will and I will file tomorrow. Does she have a chance to take what the court awarded me as administrator and give to her the lots were on MlS and being sold with some other that my aunt owns stating lots listing can be sold together or separately. She told my lawyer she doesn't have money for an attorney. She will do this herself and file her will. Now, what? They claim they have a buyer for the lots. I checked the taxes are still not paid since he passed and they are in his name only. There is no common law marriage in my state. We are sure we are not in that will she claims she is holding . Dad had dementia in the end he never handled his own life right.