Jon & Kate Plus 8

I was wondering why Jon and Kate's parents aren't involved in the show or even mentioned. Are they in their lives? They talk about other people all the time and how much they mean to them and how much they love their kids but the grandparents are never talked about. Do they live close by, have they had a falling out? We have watched the show for years and love it. The kids are so well behaved and it seems to be such a team effort by Jon and Kate and some aunts, uncles and friends but no grandparents. Are there any plans to put a time frame on how long they will continue to film their lives? Are Mady and Care getting tired of it? What will they do when it's time for the sextuplets to go off to school?