Customer, John Smith, on a consumer account with son and daughter-in-law - brings in check payable to the J A & D A Smith Living Trust, John Smith and Dolly Smith, Trustees - what options does one have?
Do both trustees have to endorse (I don't know why I'm having a brain cramp) or is the "and" in their, simply copying over that John and Dolly are both Trustees - we think Dolly just deceased - ugh - I hate April 1 - all the kookie stuff is coming out- -

It's payable to the trust, not the trustees. Unless the trust required both trustees to act in concert, either one can sign on behalf of the trust.

However, your problems are 1) you do not know whether the trust required both trustees to sign and 2) trustees are not supposed to cash checks payable to the trust. On its face it's a breach of fiduciary duty for which your bank could and should be found liable.

Uh-uh.