If you were to send my family a letter, you’d have no problem writing out the envelope. My surname is Andersen, so the etiquette rules for writing a plural last name are pretty simple: Just add s! But ...

Are the Williamses coming to your house for the holidays? Or are you going to the Williamses’? Maybe you’re planning to celebrate Christmas with the Maciases or the Sanchezes, perhaps at the Nashes’ ...