Estate Law Questions? Ask an Estate Lawyer.
Hello and thank you for the question. I am sorry to read of this dilemma.
The lease is valid
one owner has authority to bind all owners
this can be by actual, implied or apparent authority
ideally, it would be signed by both
practically and legally, signature of one owner is sufficient to bind.
I am a NY attorney and I trust the answer is fast, and acceptable.
Kindly let me know