Happy to help, Lydia! 🙂
Logan has some really good points – James did recommend aperture priority mode for that particular ACTION event. I would suggest you play around and decide for yourself. Since Logan and I came to two different conclusion, it’s likely you’ll find what works best for you. 🙂
If it were me, I’d be inclined to shoot in shutter speed priority since your dealing with moving kids, etc. But like you mentioned, moving over to aperture priority for stiller images or posed images might be a good idea. Just a thought. 🙂
Enjoy!