My 4.5 year old is anaphylactic to nuts...my 2 year old is severely
allergic to milk.  This lends itself to some interesting discussions!
When we enter a restaurant, or visit friends or relatives for meals, my
older boy always enters the scene bursting with the question  "DO YOU
HAVE FOOD THAT DOESN"T HAVE NUTS OR DAIRY!!??"  At three, he would
elaborate to a waitress or hostess about who could eat what in our
family.  With great drama...he almost seems to enjoy explaining the
whole thing, and I think because he is so strong and unapologetic about
it, people seem to enjoy checking ingredients for us...making sure that
things are safe.  We always travel with our own food for my 2 year old,
but servers will bring us clean plates, just like ours, so he can feel
like "one of the gang".

We just moved into a new house and a new neighborhood, and a neighbor
came to welcome us with a beautiful plate full of muffins.  Seth (4.5)
politely helped me ask our new neighbor about nuts, and then went on to
ask about milk (for his brother, of whom he is lovingly protective).
The neighbor felt badly for having brought a food that our younger
couldn't eat, and Seth piped up: "That's OK, he has special cookies we
keep just for him!)  The neighbor laughed along with us, and all was at
ease again!

Last week, Seth's preschool had a farewell celebration for one of the
summer teachers.  He came home excited, reporting that they had
chocolate chip cookies for the party.  My heart stopped for a second.
He proudly announced that "Miss Liz told me the cookies were
safe,'specially for ME!"  I think he thinks his food allergy is some
kind of gift!!  Go figure...it's nice to see.

I think the kids pick up your comfort level with the whole thing.  We
follow many of the same rules others have mentioned regarding food that
is not safe for one or another member of the family.  It seems to work
out.  We talk about working as a team to keep everyone's food safe for
them.  Good luck to all!!  Hope to see more on this topic on the list.
It is helpful for us parents who are trying to keep our kids safe from
one of the most ubiquitous substances in foods...DAIRY!