Once a month, my oldest son's school has a pizza night when a local pizza place will donate a portion of sales for that night to the school. My son wants to participate because he likes pizza, but also because there's a prize for the class that earns the most money through orders!
I told him I wasn't sure if we could do it. Oliver can't eat pizza and he's become increasingly aware of the fact that we often eat different food than he does. In the past month, I've really tried to make sure what we eat for dinner (the one meal we eat all together) is what he eats. This may mean boiling up rice pasta for him and regular pasta for us, or keeping sauces separate and not letting him have that, or avoiding certain dishes all together. I can't let us eat pizza while he isn't. I decided to make him a tortilla pizza (since I had some wheat-free tortillas in the freezer) topped with daiya cheese and pepperoni. He didn't eat it, but he also didn't beg for what was on our plates.
Clearly, it's going to be difficult to be "fair" to all my kids. The big ones shouldn't have to always miss out on things like this, but Oliver shouldn't have to be left out either.