Thanks for the response.  I was unable to merge the accounts after trying all of the things you suggest, and I was on the phone with tech support the whole time I tried these things.  Tech support was unable to help or tell me why I couldn't merge them.

I have taken your suggestion about undo-ing all the reconciliations and trying to start over.  The bank account was opened 3/1/22 so it's only 15 months of recs.  When I undid all reconciliations and went back to start with 3/31/22 there is a beginning balance of $16949.50!  Which doesn't appear in the bank register as an opening balance.  The bank register, at least for the first month of transactions, is as it should be.  I have no idea how QBO came up with a starting balance that doesn't exist.  The starting balance should be 0.00.  I'm seriously at my wit's end over this and about ready to re-start this client in desktop.  It's ridiculous!