I did get it solved and received the refund check without issue. Here's what worked for me:
At the top or the return, form 1040, p. 1, I entered by hand, "[name] Deceased [date]."
I used only the SS# on the 1040--no EIN. Before filing, I applied for and received an EIN for the trust. I later learned that the EIN would only apply to a return in the name of the trust—in my case, the 2021 return.
I filed a 1310 with the return. In parts I and II, I stated that there WAS a will, and that a court had NOT appointed a pers. rep., and would NOT be appointing one. (This was the key.)
Before filing the return I sent in a form 56 and noted on the return that I had done so. You could just send it in with the return, however. In section A, I indicated "e" (Valid trust instrument and amendments.) On line 2b, I entered the date of death.
Every time a signature was required I appended "successor trustee."
That was it. I hope this helps.
