I have out-of-state relatives who come and stay at my in-law's house. We never know when they're coming, but are expected to drop everything when they arrive. What would you suggest.

I’m so tired of it. I would prefer knowing ahead of time so I won’t have to cancel my previous plans when they show up. It’s nice to chat, but I’d like to know beforehand that they are coming so I can meet them for a meal or activity rather than sit for hours.

Yes, you can make your wishes known. What you are proposing is common sense and common courtesy. Tell these relatives you love seeing them but would like some advance notice when they plan to be in town so you can adjust your schedule and take them somewhere rather than sit for hours at your in-laws’.