Definitely use the curved screen submix. It's very reliable, I would try to get a Triplehead2go on it so that you can just use same layer and it will be guaranteed to stay in sync.

This way you could control the 3 way tile with one long piece or 3 separate pieces if you want. If you don't need to spread one image all the way across, I would still use the internal curved screen control on the submixes that you are needing for and use 2 machines for it, unless of course it is a very small resolution screen...

Alternatively, if you need absolute seamless screen blending with point control for luminosity, you could use a Spider but to me it sounds like Submix curve screen would work just fine in this situation. Even Catalysts Blending is completely and totally awesome, stack right up to a spider with a few small exceptions.

Hope this helps

Kindly,

Christian Choi