Parents usually have blinkers on when it comes to their child because they truly do think their child is more special than anyone else's.
I know for a fact that my own kids are the best kids on the planet...
So when I get an over-zealous parent ask for a ton of 'special"...I smile sweetly and tell them all the same thing.
"Before you ask me for any special favors..please remember I have to treat all the children (and parents) the same. Ask yourself if your request is reasonable multiplied 16 times."
A lot of the time they THEN wake up and see it's just not going to work in a group setting.