Yes.
At blue bayou, they will charge a split plate fee of 4 or 5 dollars, but that gives you two nicely plated portions, and each of you will get your own salad, and enough bread on the table.
Other places don't seem to care who eats what.
The other option, if the 11 year old can handle it, is ordering kid's meals. I did that, though not with table service (just didn't eat table service on the trip), in January just for myself!