I just was hoping it would also be a
feature I could utilize given my
ambitions with this new toy
I used to run both crossfire and sli, and even had a dedicated physics card at some point. But the software support was generally lacking. Switched back to a single powerful GPU and never looked back. 
Would love to see some proper dedication to making it work to be honest.
But nah, historically UE4 has not supported multiple gpus. I believe the sli / crossfire support has to be worked into the final product by the developer.
I wouldn’t mind having a couple of extra eGPUs waiting to kick in only when I need some parallel number crunching backup.