^^^^ This is the first thing I thought when I read your comment about JO qualifying ^^^^
Softball teams always need speed. If she wants to make the HS team, work on bunting and slapping; and they will find a spot for her if she can put the ball in play and get on base. It sounds like track is her sport, so I wouldn't recommend missing meets to play softball.
You may be able to find a travel softball coach who will allow her to join as a "practice" player. Attend as many practices as possible and tourneys, knowing that she may see limited playing time. The growth will come from having regular practices for the most part anyway.
But come HS tryouts, bring that speed!!
she might also have opportunities to guest play if she regularly practices with a team (injuries, illness, vacation, etc.).