I added a buh-bye outside tag. It will take you to lots of ideas.
This was my advice in 2012, still applies today.
"Switch to the Buh-Bye Outside Program.
AKA, Kiss-N-Go. Been around and effective since the 70's.
Lock doors, have children dressed and ready to go home....then meet them at the door.
Simple solution. Works wonders. Adults should never have access to other peoples children unless they are on the pick-up list."