There's a fine line in parenting that I can't fully define. You'll know it when you see it in your own family, though.
It's the sibling-retrieval line.
You see, when the 2 yo or 4 yo runs away, and the 7 year old volunteers to retrieve them. That is disaster. You just end up with several children running chaotically around and yelling.
If the 9 yo offers to retrieve the wayward child, he runs after the child and the child runs faster. Then you have two children running further and further away ... hopefully not into traffic.
For some reason, it seems to work (most of the time) if the older sibling is 11. It works almost all of the time if the sibling is 13 or older.
I don't know what makes the difference between a 9 yo and an 11 yo retrieving a wayward toddler. But it just seems to be true. I don't think it's the size of the older child being more intimidating to the toddler. Sometimes I think it's wisdom of the older child to know when to walk slowly and calmly, and when to make a fast grab.
Toddler retrieval must be a skill learned with age and maturity. Now if only they learned how to tune out noisy or whiny 2-7 year olds in the car at that age. That apparently takes more time ... or else the distance that being in the front row provides.
Still recovering from the family field trip,