Multivitamins – children's or adult?

I’m just curious as to when you switch over to adult multivitamins for your older children. The labels for most OTC medicines often dose for “adults and children 12 & over.” I’m wondering if it’s similar for vitamins. 

My oldest (14) is almost my size, but my younger two are both a little bit small for their ages. I’m wondering how any of you have determined when to switch.

I would just call and ask the pediatrician, but we have health insurance that “assigns” you a doctor and then you have to wait until November to change if you want to. Just this past February, they assigned my kids a new pediatrician (male) for some reason, and we can’t change until November….and my girls don’t want to see a male doctor, so we haven’t seen this doctor yet.