I was going to say, price it up without the dining plan, but I see in the OP, she wants food included. My son’s family was with us last week and the kids and their mom eat almost nothing, plus DS watches what he eats. It probably wouldn’t be the best thing for them but they did buy the mugs. (Dining plan still includes those, I imagine.)
One thing I’d pass along to your neighbor is to start including Disney items (clothing, accessories, etc.) and gift cards for birthdays and holidays for this year and up until the time they go. That helps a lot with costs while there and in planning outfits and packing.