A little bit of a back story to begin with:
I have two daughters ages 3 and 9, and two step daughters ages 22 and 19. SD1 is officially graduated and SD2 just ended her second year. Both SD's went to college far away - one 18 hours and the other 6 - not so easy to visit during the year. We live an hour from SD's moms house.
The first time SD1 came home in October she didn't think that she would be able to see DDs as it was only a four day break, so we didn't tell them. She ended up working it out and asked us to keep it a secret - so we did. DD1 had a priceless reaction and was overjoyed to see her big sister again. For Christmas break they both knew that SD2 was coming home, but we surprised them again in February and again just this past weekend after her mom and stepdad got her moved out of college.
DD2 stopped sleeping over at our house at the age of 15 for a variety of reasons that are too long to get into right now. DD1 was 18 at the time, and in college. The custody arrangement ceases at the age of 18, I know - but the girls are required to adhere to visitation as long as we are paying for their college education. We don't force the girls to sleep over, but when they do its treated as a large treat - because it is. While DD's do see their sisters once or twice a week, they love having them sleep over. (This happens every other Thanksgiving, Christmas, one weekend in February and Easter.) When they're here we play games and bake cookies and do anything DDs want to do. The girls have a later bed time too.
Today DH and my SD's got in a large fight and they declared they reached their 'boiling point' - they say they hate coming to stay the night because we always make a big deal out of it. They said that because their sisters are always around they don't spend time with their dad. SD2 didn't like that we made her last two homecomings a 'surprise' (this was our fault - I thought DH had told her the girls didn't know she was coming to dinner - he didn't.) In response to that, well, it is a big deal! Neither of them have spent more than one weekend every few months here in at least three years. Their sisters only see them for a few hours a week, and SD2 even less because she's been out of state for nine months. Of course their sisters and their dad miss them and want to spend a lot of time with them. And DH wants to spend time with all his daughters. He has a full brother 15 years his senior who moved away when he was five and has minimal communication with and DH doesn't want that for his daughters. If they were around more it wouldn't be such a big deal to the DD's.
This is more of a rant than anything else I guess.
Do you make a big deal out of it when your (older) step kids are home? Or your kids in general are home from college? I know I (read: DH) can't force them to stay over more, but would the suggestion make it worse or better? Basically I want to continue to encourage a relationship with their sisters and don't know how else to do it.