Transportation equipment

I currently have two 19 months old and may care for another 18 months old. I also have to walk to school for drop offs and pick ups. Right now it works as I have a twin stroller or double wagon to use. The walk to school is about 15 minutes.

What do other do or use for little ones where the walk is to much? What about when it rains, do you have enough car seats to transport them that way?

Probably getting a bigger wagon would serve you the best for now if you are used to using a wagon now.