Yes, have the child be part of the process, but do this BEFORE the server takes the order. Having children be decision makers early in life makes them better adults. But having them make choices at the expense of others is just bad policy. A child ready to order impresses a good server and this shines well on you as a parent. Politeness is a virtue. I see this from both perspectives. Have been a parent and a Denny's server, so I agree with all of the above to a large extent.