When they show up unannounced

I have some in-law family members who show up unannounced. There are times where I don’t mind but sometimes it’s not the right time and they are at the front door. Sometimes, they say they just drove by and bring food or snacks or clothes for the kids and it seems like their excuse to drop unannounced. It’s really kind but nowadays the possibility getting in touch are there. I’m not sure how to nicely tell them to call next time.

!Edited! It’s not a good time because it has happened while having sex with my husband, or just unwinding, or just time to myself when the kids aren’t home. Or the kids are eating, sleeping. There’s many reasons you just don’t want a pop up