Hey,

I know with UE4 the options for AA are limited due to the deffered rendering path. Have you guys looked at TAA?

I know it can give a slightly blurry image, however there was an UE4 document released which perhaps the devs could look at which may help with that?
https://forums.unrealengine.com/development-discussion/rendering/1449167-sharper-image-without-the-edge-artifacts

Thanks for reading.

Ben.