Okay, coming in again a full year and change later...
There's a big difference between sending something back because it was prepared incorrectly and sending something back simply because you don't like it or didn't know what was in it.
I can't sell that order of pasta with anchovies (that was clearly listed on the menu as a main ingredient) to another person like it was a dress you tried on but didn't like. If you order it, and I do it right, it's yours. If I do it wrong, I'll replace it with my apology.
As for having a child complain to a manager or a server, I wouldn't deal with a child. It's one thing for a kid to tell you how much they love their pancakes, but another thing for a kid to complain to a staff member. These are adults trying to do a job. It's not the place of a child to make corrections. An adult in the party should speak for a child if a mistake has been made.