I would say that with this crew at Disney you probably need some help. We brought our twins to WDW several times when they were toddlers and our older daughter was in early elementary school. As I'm sure you know, each of those twins need near constant supervision. And then what do with the older ones? Our solution was to bring our long-time babysitter with us. We managed this by staying in a
two-bedroom villa at the Beach Club (they sleep eight people). Our sitter was kind enough to bunk with the girls. The extra pair of eyes was indispensable. Another great way to get extra help would be to bring along the grandparents or an aunt.
Even if you can't bring helpers for the entire trip, you can make sure each of your children gets some special time (and you retain at least some of your sanity) by using some of the babysitting options available on property. Many of the WDW resorts offer
childcare centers for kids ages 4-12. You could leave your older children there while you devote a late afternoon (when the centers open) to sharing Fantasyland with your twins. Or you could leave your twins with an in-room sitter (Kid's Nite Out) and take your older children to a special Extra Magic evening in one of the parks. To contact Kid's Nite Out, call (407) 828-0920 from 8:00 am to 9:00 pm, seven days a week.
Good luck with your trip!