If you can get logins for some of your other group "leads" you can login as them and be working on 2 at once. 2 screens on your computer or computer/tablet and/or phone combos. I would advise in planning to have the group separated more than together with times to be all together each day (meals, fireworks, parades, etc.). When you get more than 5-6 to a group, it is hard to move through the parks, let people see what they want, and keep a good pace for everyone's needs. This would also keep you from having to have exact or overlapping times for everything, as you can prioritize the mountains for the young adults, fantasyland for the littles and then split the adults by their preferences.