I think you may be able to string this along indefinitely. When your people visit, special events get planned. On meeting nights or Sunday, get tickets to a game or a play, go to natural attraction, plan a special meal-either at home or a nice restaurant. After all-how much time do you have to spend together catching up on life these days.
When most JWs vacation, they don't go to the meetings (unless they are vacationing with JWs that are not related). If these folks were suspicious, or if they were dead set on going to meetings, they would have called ahead to the Kingdom Hall in your area, thus finding out you have faded. That they have not done this thus far is telling. Either they don't care, or they don't want to know. Either way, you are in a don't ask don't tell sort of relationship with these guys.
Sounds like a good thing, until some event forces the issue, just enjoy.
Shoshana