Unfortunately, there is a known issue with some of Apple's recent iPads where they won't pair with more than 1 or maybe 2 Bluetooth devices at a time. There's a long thread about this problem here:
https://www.eventideaudio.com/community/forum/stompboxes/bluetooth-issue-2-h9s-simultaneously
I don't have anything new to add to what's already been said in that thread. We registered a bug report with Apple and sent them Bluetooth diagnostic logs as well as three H9s to test with. They made a change in iOS 8 that fixed the problem for some people, but other people are still having the same problem.
