Our group insurance covers anyone to fly as long as either one of us is flying with them OR they have flown with one of the group and they judge them to be competent. So on that side AN Other would be covered.
As regards them flying as PIC, if I was flying with a pilot mate and they said 'Hey I will pay half if you let me log half PIC' (such as EA when he gets of his fat Southern @rse and gets it up here
), they I would have no problem with that - I dont see it as the group losing out, in fact I see it as an advantage as the aircraft is not sitting on the ground and is flying!
J.