My friend's son had poor neck control untill about 6-7 months. He had really bad reflux and the doc told her because it hurt so much for him that he just didn't want to hold it up alone. Not sure if this helps. Sorry.

hi my daughter is 5month old she still don't have good neck control can u tell me when did your baby got neck control?

Some babys just develope faster or slower then others.
I wouldnt be too concerned for it at this point.
..but if you are i would ask her doctor.