Depending on how busy the parks are, Disney may not allow you that option.
If that happens then fine, no biggie. But we go, at least in the past, anywhere from 5-10 times a year and we have never run into them not allowing this. We sit, DH and son brings the food, we eat quickly and get up, clean up and leave. It causes fewer problems than all of us hanging out in the line to order food or worse, if WDW is that busy, hanging out waiting for DH to order and the remainder of us getting in everyones way. Also, living as close as we do, we typically don't go when the crowd levels are that high, I refuse to do that.