You are going to need an attorney. Just to place a lien, you'll need a "deficiency judgement". Normally, your uncle just telling you he was going to leave it to you is not sufficient to inherit. It needs to be in a will, properly drawn up and executed. Without a proper will, property usually goes to the next of kin and what you have done for the family will be ignored in the legal process. Have you discussed your concerns with your cousins (in a friendly way)?