Well it’s just a matter of basic understanding of how light and reflections work really.
I thought of using dot product as an indication for the angle from which the player is looking at the mirror, and rotating the scenecapture2d away from that angle accordingly. E.g. the more the camera is looking at the mirror from an angle, the more the scencapture2d should be looking directly away from the player. (player goes left, camera turns to the players right, player goes up camera turns down, etc)
The answer is already kinda available here Realistic mirror reflection vector with SceneCapture actor?
Just a matter of figuring out how to apply it in bp really.