My family homeschools, and we had something similiar come up at a park day outing.
One of the women there had vegan children, and there was a pot luck picnic going on. Of course, almost all of the dishes had meat in them and most of the ones that lacked meat were not vegan. So, the kids just kind of sat there watching all their friends eat. They had packed lunches of course and their mom had brought a covered dish that was vegan, and so had I but they felt left out. She felt bad and ended up letting them have some cookies that weren't vegan because they kept asking her over and over.
I'm sure this situation is going to come up more than I want it to once Ares is old enough to decide what he wants to eat. His dad eats meat, and we really haven't talked about Ares being vegan. I want him to atleast be vegetarian until he can make his own decisions.
Most of the time, her kids never seemed to ask her if they could order stuff that had meat in it. When ever we went out to lunch with her family, they would always order something that was vegan or atleast vegetarian. I think it has a lot to do with them seeing other people eating things they can't eat, and they get curious.