From a priest:
I have a multiple child Baptism coming up. My question is if one priest can supply all the various ceremonies and multiple priests celebrate the Baptism proper for the various children in the older Rituale?
Hmmm… no, not really. That makes the right confusing, at best.
Just follow the Rituale. Some things you have to do with each child individually, such as exorcisms, something can be done by all the godparents together, such as certain responses to questions and the recitation of the Creed.
Depending on how many there are, if you don’t have a great memory, you may need a little “label” on the kids with their names, or have a godparent hold one, for moments like the imposition of salt. Also have a list tucked into the book with all their names in the proper Latin (or English) forms, for moments when you can say one prayer over all of them.
If you try to force everything to be “meaningful” – looking around with significant eye contact and earnest expressions at every other word – you will be there all day.
Keep it moving and it won’t take that long.
And try not to let the inevitable din distract you from pushing forward.