Also a violinist here, though nowhere near as good as Endre.
I agree with what he said 100%, especially with #2 and #3. My problem with #3 is nobody plays like that; the attempt at an illusion is more obvious to me than the illusion. Fortunately you will get away with it with the vast majority of people.
For trying to capture motion in a still frame, you may consider experimenting with repeating strobe or rear curtain sync. It admittedly will be much more tricky to coach her through the movements you need while keeping everything else still.
I personally think #2 is the strongest of the three. I'm sure Sydney loved them all!
THanks, everyone! I haven't been on here for a few days so hadn't realized there were so many comments! I normally like to respond to each comment personally but can't get to it right now. Just wanted to tell everyone I really appreciate the feedback -- in this case, especially from Endre and Oscar! Have a great day!