GlidePort.aero is the best option for real-time tracking. It combines Spot, InReach and cell phone traces into one contest focused viewer. You see details of the competition including the task.

http://ssa.org/sailplanetracker is mostly the same thing, just a different name.

GlidePort will not sync the starts but it does allow play back.

Search "GlidePort.aero" on YouTube to see a video of how to use it.