When I first moved here my sister would drop by unannounced. I finally got her to call first but now she calls from two blocks away. She lives 30 minutes away. Help!
I don't think there is much you can do. Have you thought of not answering the door? How would she know you were there? That's about the only way you could avoid her.
Some people are just that way and family more then others I think. I like to know when someone is coming by because I am one of those that doesn't always have a spic and span house! I like company but would like to have the clean house too.
I don't like pop ins. I am pretty lucky that everyone I know calls me well in advance of wanting to stop by. You just have to ask her to give you more notice.