DEAR MISS MANNERS: You addressed the thorny issue of sending a letter to a lesbian couple who share a last name (The Mses. Jones). Nicely done.
But what of gay male couples with a shared name? "The Mrs. Jones" would seem to miss entirely. "The Mres. Jones" mangles standard English plurals. What to do?
GENTLE READER: The correct plural abbreviation is "Messrs.," as it could also be "Mesdames" for the ladies. But you could also spell out "The Misters Bob and Thaddeus Jones."
Miss Manners maintains that abbreviations are not helpful shortcuts if no one knows what exactly they are abbreviating.