I am one of those Mom's who doesn't want her kids to miss out on anything, so am willing to waste my entire weekend running my 2 DSs all over so they don't have to miss out on a single game, party, or whatever. I, too, was stressing a bit when I started looking at the kids schedules and saw that stuff was going to overlap. I posted a similar question, and one response I got was basically yes, things were going to conflict, and yes, decisions would have to be made.
That being said, everything turned out fine. It was only the 4 of us, so we didn't have the in-law dinner rule, but we had late seating and did eat every meal together. One of my biggest concerns was that the boys would miss flubber-making - well, I think one made it and the other didn't and he didn't even care!
You really have to look at the big picture. What activities do your kids enjoy. What are their must dos - have you actually asked them? (I would have thought both my DSs really wanted to make flubber!) Is the night of the most fun thing ever in the kids club also the night of the easy-to-miss show? Can you plan an adults-only dinner at Palo's for a night there is something the kids want to do, releasing them from the family-dining restriction? Maybe eating dinner together most nights will be good enough for your in-laws, as long as you're getting together for breakfast and/or lunch? Although my DSs loved most activities, I've read other posting where the kids never warmed up to the kids clubs, so it wasn't even an issue.
You didn't mention the ages of your kids or which cruise you are on, so that could make a big difference too. No matter how much fun an activity seems on paper, the kids may not have the energy after all day on the beach. There are just so many variables that I found that there's no way to truly plan for everything and count on it working out.
My best advice would be to show your kids the navigator and review the possible activites in relation to the other things scheduled - sea days vs. ports, shows, meals - and let them help with the planning. If they know up front that they have to choose between flubber and Hercules, they will have had time to think about what they think they will like best. If you let them know they won't be able to do any kids activities during the dinner times, they won't be as disappointed on the cruise, or maybe they can start turning on the charm with Grandma and Grandpa to be excused just once! If they are very young, they will probably not even know what they are missing, so just tell yourself that you will do it differently on the next cruise!
No matter what you do or what you miss, enjoy!
