My lovely sister, Anne, sent me a question this week. She wanted to know how to indicate a possessive that belongs to two people, i.e. the wedding of Jenn and James. She writes, “I think I remember something like if it belongs to them together, the last person gets the apostrophe. Did I just make that up?”
No, you’re absolutely right! The Chicago Manual of Style notes that, “Closely linked nouns are often considered a single unit in forming the possessive, when the entity possessed is the same for both.” e.g. Over the weekend, Anne stood up in Jenn and James’ wedding. But: Katie’s and Anne’s weddings were simple, elegant affairs. 🙂
Send me your grammar/style questions and I’ll do my best to answer them!