You want to go to an instructor to learn new things or solve problems.
If your DD is already an experienced pitcher maybe all she needs is some practice to knock off the rust. Then you might notice some problems that an instructor could help you with.
Seeing an instructor doesn't have to be a weekly thing - if your DD is willing to practice on her own you may only need to see the instructor occasionally.
I think a 16U pitcher will need a movement pitch in addition to an accurate fastball and change up in order to be successful.
If your DD is already an experienced pitcher maybe all she needs is some practice to knock off the rust. Then you might notice some problems that an instructor could help you with.
Seeing an instructor doesn't have to be a weekly thing - if your DD is willing to practice on her own you may only need to see the instructor occasionally.
I think a 16U pitcher will need a movement pitch in addition to an accurate fastball and change up in order to be successful.