Don't worry about it. It would be nice to have the perfect family, but let's face it none of us do. They have lived long enough that they now have the life that they want; they don't have to work around kids anymore, they come and go as they please.
Don't entertain them when they visit. If they just want to hang around the house, enjoy the short 5 days. Prepare for their visit by having food prepared ahead, do the wash after they leave, and just take a little vacation yourself - it's only 5 days. Roll with it, you're not a maid, room service, or a kid, you're a grown person with kids.
Enjoy your time together, see how that that works.
Linda