We typically spend over 20 hours doing our best to place campers into units where they will have a fun time at camp.
The primary rules we use are done in this order:
1) Friend requests: We determine if the two friends listed are attending camp. If they are, we put the friends together. Problems can occur if the friends name is incorrect, misspelled, or no last name is given. We cannot honor friend requests if the age difference is outside the Girl Scout level (Daisy, Brownie, Junior). If numerous girls cross reference each other creating a group that is larger than 10 girls for Daisys or 12 girls for Brownies and Juniors, we have to place them into multiple units. 10 and 12 are our maximum unit sizes.
2) Troop Number: we put girls in the same troop together. There are occasions where we may need to split a troop into 2 different units due to needing to build units that do not exceed the maximum size.
3) What school they attend: if a girl is the only member of her troop attending and she has made no friend requests, then we try and place her with girls from her school.
On top of placing campers into units based on the above, there are also volunteer adults that need to be placed into each unit. The adults also make requests on whether they must be with their daughter, prefer to be with their daughter, or are willing to be placed where we need them.
Hopefully you can get a feel of the puzzle that needs to be pieced together when we are dealing with 300 plus people attending camp.