Most restaurants will let you sub a side dish from one entree for a side dish from another entree, but I didn't see spaghetti as a side for any of the VN entrees so it might not be possible. I recall that someone posted quite a while ago that they wanted this same substitution at VN and it wasn't allowed back then. You will have to ask and if it isn't allowed there is a spaghetti entree on the kids' menu that you could order or convince someone in your group to order the adult spaghetti entree to share with you.