I have 2 kids. Before their bikes were stolen (recovered one- which was stolen again and recovered), I had them ride to the front. I'm the biggest of the bunch and so present the biggest target for approaching traffic from behind. If I noticed we were approaching something dicey, I could easily either instruct the one in front of me to pull off to the side/get out of the street and pass that along (though I've had to chase the lead down because he didn't/couldn't hear his sister) and we would regroup or I would have her edge right while I moved further out in the lane and we both chased the lead down.