My brother is going through some tough times so I offered to flip the bill for a S5 for his daughter and to add her to my plan. I have a 30g plan which I though was a rather large plan. Between the other phones and using the hotspot for work I still had roll over ever month. Introduce the niece. On a regular basis she uses at least 5 gig a month Some months as high as 9gig. I have paid overages since she has been on the plan. I decided that she was going to be limited to 4gig a month. Her mother, I don't really care for her, texted me saying she called att and they said she had plenty of data left. She is too stupid to understand how shared data works. Is 4 gig a month reasonable for a 16yo?