What is the difference between ながら, がてら and つつ?
ながら means doing multiple things simultaneously.
がてら means to do one thing at somewhere middle along way to doing another.
つつ means doing multiple things alongside but not necessarily simultaneously, little by little in turn.
'eat while driving'
'eating along the way driving (after having driven half way)'
'take a bite and drive a little, take a bite and drive a little, ...'
I think the meaning is to drive half the journey (for example) stop for food and then drive again to.the destination.
"We stopped for food on the way here"