Teens and Babies
I have so many mods I can't remember what all I have, and don't have
It is a big help with the bigger families, but I'll play around with it and see if that is what's causing sims to carry babies, and toddlers to school, or work.
But indeed, if that action includes carrying a baby or toddler, they WILL forget to drop it, and thus take it with them.
The only way I know of to prevent that, is to plan the given actions so that they will NOT be carrying any kids at the moment the bus/carpool pulls up. Or to cancel their actions - including the order to get in the car/bus -, order them to put the kid down, and then order them to go to work/school.
The kind of mod you're actually asking for, would need to check for each sim if they're doing anything that involves carrying a child, and then insert an extra command in the queue for them to drop that kid, before the order to get on the bus/in the car. If anything, this will be very hard to do. I'll put it on my list, Becca, but I advise you NOT to hold your breath, because it may take a long while before I've figured this one out.