Thanks everyone for their replies.
Army Judge - We do have an attorney engaged that had done a great job with other litigation involving the estate and other assets. However he has had limited experience with promissory notes.
Adjuster Jack - I agree that option 2 would be the best...
Handling an estate as administrator and am also one of the three heirs. The estate is basically split 3 ways and we three siblings have no issues with anything in the planned distribution of the remainder of the assets. We are however struggling on how to approach the promissory notes...