Sorry if I missed this somewhere but which is the primary device. By this which takes priority.I flew my motor glider a couple of times today. 

On the second flight I tapped loiter on my tablet from stabilize selected on my RC tx. Off into loiter it went. Lovely thinks me.

Then I selected stabilize on my RC tx back into stabilize it goes. Top notch.

Now thinks I what will happen if my radio goes into failsafe after my last mode selection was via tablet....

Sorry if there already has been an answer to this or a blindingly obvious resolution.