Baby who doesn’t want to be put down

I am one of 2 lead teachers in an infant room at a Montessori school. We have 8 infants currently. Our youngest, 4 months, does not tolerate being put down and cries immediately. This includes if we are sitting right next to them and touching them. I suspect their parents must hold them a lot at home which I don’t wish to address with them.

I was wondering if there was any advice anyone on how we can help them to be more comfortable on their own in moments when we have to help other kids, and obviously because we can’t hold a child all day and I want them to be able to play independently as they continue to grow. Thanks in advance!