What about homemade burgers?
I often do a 'build your own burger' themed meal when having kids over.
Make your own homemade burgers (beef, turkey or even lamb)
Have crispy fresh rolls, cut & buttered, with a selection of:
lettuce, tomatoes, sliced cucumbers, sliced gherkins, caramelised onions, difference cheeses, avocado (I usually have crispy bacon too, but you obviously wouldn't on this occasion)
have different sauces offer tomato ketchup, burger sauce, BBQ sauce, sweet chilli etc.
Adults & kids can create their own burgers according to their own taste.
I would serve with potato wedges & garlic mayo.