multiple pilots

I want to fly a new drone that I bought for my son. I crashed his original one, which he had registered with the FAA under his name back in December 2016. Now I want to register the new one so that I can fly it and be in compliance. It is his drone though... so will he be legal to fly this...

This past weekend there were two of us flying Phantom 3 Pros. I have an IPAD Mini 2 and the other guy had an IPAD Air 2. Every time we stood within 6 feet of each other his video would cut out while mine remained steady. We tested it several times even after a reboot and new batteries with the...