A promissory note, in and of itself, does not entitle you to a lien against the home. To obtain a lien, you would first need to obtain a judgment. Meaning, you would need to file a civil lawsuit against him over the promissory note.
If I'm understanding the situation correctly, he only recently provided the promissory note. Further, the note only indicates that he will pay the monies when he sells his home. Candidly, this does not leave you with a compelling lawsuit. My thought, unfortunately, is that the court would rule against you as your brother has not yet violated the terms of the note.
So, as I see it, your options are to wait it out for him to sell the house or file a lawsuit that you will likely lose in the hopes of trying to force the issue.
Please let me know if anything requires clarification.
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