Can you do a shortened visit? I get that coming from 3,000 miles is a long way, but 7 days is a long time for anyone no matter the distance. I wonder if you suggest to shorten the trip they would just not come?

OP here - thanks for the suggestions. Despite the tangents on treating in-laws like parents, there were some really thoughtful posts, and I appreciate them. DH will be the one telling them, but he was getting stressed about it and I wanted to help with some ideas of how to handle the conversation with his parents. Actually, he wants them to visit less than I do; he has a loving but pretty superficial relationship with his parents, and wants to keep it that way.

Thanks again for the useful ideas.

If they are on the same page, her DH should have no problem handling this. No need to add in law issues to an already troubled marriage.