When I had mixed ages we split our time between the baby area and the big kid area. In the baby area the big kids had brought things to do or helped the little ones. In the big kid area the babies played in the sand near the structure while the big kids played on the structure. Swings were off limits because I was not able to leave the babies. They became a treat for my own kids when we went to the park evenings and weekends. Limit what toys you take from home to the park and make more use of the park facilities if you can.

Also set a rule that no child can move more than 5 feet from you without permission. Pair up an older child and a younger child and their job is to follow the child around in the kiddie park and then after awhile they get to go to the big park while you watch the babies near by.

If the kids are not able to do the item on their own they don't get to do it. I don't lift, catch, hold the big kids at all. They are responsible for their own comfort zone on the climbers.

Try going to the park at a different time when it might be less busy or be a different group of kids.