Make a spreadsheet!
I can't tell you how much my life has depended on spreadsheets. I learned how to make them early on and I use them often.
Here is a spreadsheet I created for one day of play practice. One day, mind you, although this encompasses ten people from two families. Still...
Instead of complaining, and since it is the month of thankfulness and not crabbiness, I'll just say how thankful I am that I enjoy creating organization out of challenges such as this: How to get 10 people to and from practice (which is a 35 min drive) in the fewest amount of trips (and cars) possible so as not to cause children and adults to hang around for hours doing nothing.