I have leashes attached to my stroller. My 2 three year olds hold them and if they let go it gets attached to their wrist (only happened once). I have the backpacks as well and I have only used them when we go for a walk on a really busy major street (I live downtown Toronto). If a kid is having a hard day and I have a spot in the stroller they get put in there. New kids are always attached to the strap by the wrist until I can trust them/they understand the rules. Kids also always walk on the side of the stroller away from the cars (they will switch sides when I tell them to) so there is an extra buffer between the kids and the cars. I bought my backpacks on ebay for $3 from China. They are cute bat wings so the kids love them.