I've been using SD with a SkyEcho with good results, however recently on a flight a firmware glitch caused my SkyEcho to drop the wifi network, which obviously then caused Skydemon to lose GPS position. I use an iPad with internal GPS, and I wondered is it possible to switch to this in flight, as the only way I could find to force it was to stop navigation and restart with the internal GPS.

I would see it almost as an expected feature. I must admit that I assumed I had missed something in set-up to allow this to work, and was a bit surprised to find out that it is not currently possible. It would generally speaking mimic what must be commonplace system behaviour, that if you have two inputs available and one fails, the second is automatically switched to.