I would let her know that while you understand that it is difficult being away from her child-you can not be updating her constantly-because you have to focus on...her child!

Do you do journals or info sheets? I have a communication journal for each child that gets sent home with them each day. Parents read and sign it before sending them back to me in the morning. Maybe offer to do that? (if it works for you).

You could just text back and say, "sorry, I just got your texts. I am unable to update often throughout the day as I am with the children, but I can send home a journal with the important info if you like".

Hope that helps!