[iTunes] Cannot connect more than 5 AppleTV

I tried to connect a bunch of Apple TVs to synchronize photos and music. I was surprised to suddenly get the message that I am just allowed to connect 5 AppleTV so I was prompted to disconnect one before connecting the 6th.

I suppose this is triggered in the iTunes. and I really cannot understand the reason why and noone has informed me about that limit before purchasing all my units.

Does anyone now a hack solving that problem?

If not, would anyone be interested doing it for a small fee?