I don’t think it helps or hurts. My middle child did shotput and was very good at it...won the district meet her freshman year and there were girls there 3 times her size, but I honestly couldn’t tell a difference in it helping or hurting playing softball.
DD plays Varsity softball and throws shot for the Varsity team as well, during the same season(spring) I have seen no ill effects at all. In fact I think it has helped her leg drive as a pitcher. Or it’s just an extra workout to get stronger!!
I am a high school throws coach for track. As long as she is taught properly she will be fine. If she trys to throw the shot like a softball then yes, she could really damage her shoulder. To get her started go to Arete Throws Nation, that is great site to get her started on the basics for throwing the shot and Discus. The shot and discus will absolutely help with her rotational power and overall explosiveness.