I loaned a family member money to buy property. They have defaulted on the agreement can I file a lien againt the property?

File suit, win a judgement, then file a judgement lien. Your promissory note and lien should have been filed at the time of the loan.

With your proof of the loan you file a law suit and after you win

What was signed at the time? What proof do you have of the loan and its purpose?