Multiple meshes collision all together?

I’m kinda new to the modelling and UE4 world but I can handle myself most of the times … but I need your help this time. :slight_smile:

Ive got this map I’m testing in UE4 from another game (Soldier of Fortune 2, I couldve used my own map but it’s just a test so don’t bother)
I’ve got the map in FBX format from BSP.

The problem is, I imported the map with all mesh being seperate (2777 to be exact) and theres no collision, so when I’d like to use complex collision, I’d have to do all 2777 seperatly which takes a hell of time. So is there any way to speed this up?

Reason why I dont import it as 1 mesh : I get issues with the UV when building the light. It says the UV are overlapping and I have no idea how to properly fix that either. So the 2777 is kinda a workaround for that issue.