Tracking points between Garmin 66i units.

My son and I hunt different areas and want to keep an eye on each other while we hunt. Can we share tracking between units automatically (like every 10 minutes)? It’s a safety thing for me to know where he is at all times without relying on him sending me a tracking point manually . I won’t have internet signal so can’t use mapshare to track him so I need to be able to track him from my 66i unit 

can anyone help ?