If you are the only one that truly touches the food and/or the other ones know the rules and strictly adhere to them (you too).
It can be done. My son is just not capable. For now.
My husband fixes himself snacks and sandwiches and occasionally makes lunch or toast for our children who are 3 and 4 years old. So in otherwords I do almost all of it they do just enough to cross contaminate food!!! The first weekend after being diagnoised my dh got a peice of toast stuck in the toaster so he "cleaned" it out and left a pile of crumbs all over the counter for me to clean up!!! And as of right now we have 3 cubes (the 1/2 cup) of butter in different amounts sitting on the counter because I will use one and set it aside for it to be mine and then dh comes in and see's that butter sitting there and decides to use it instead of "his" container of butter ugh!!!