I think that there are many ways to translate Genesis 21:14 once you make
"Hagar there" into "their being driven away", and I have one more guess.
Maybe it says that Abraham took food and a container of water, "and he gave
to their being driven out upon her shoulder and with (alef tav) the boy."
Maybe he gave both of them food to carry, some on her shoulder and some with
the boy. I am not sure if it sounds ok in Hebrew.