Not a problem. My 13 year old grandson does this all of the time here. He usually gets the bar-b-q filet and asks for the sauce on the side (not sure if he would like it) and gets fries in the place of mashed potatoes. I also do this as we eat here about 4-5 times a year (ok, maybe more). I get the asparagras in the place of the potatoes. (Since everyone serves mashed potatoes, it gets a little old after a couple of nights of them.) You will find if you ask at every locations, most of the places are extremely accommodating. My grandson is a Disney adult (at 13) and will modify almost all of his adult entrees.