Thanks for the like guys…
@sitrec ; interiors on ground floor would work, but anything spawned by blueprint will not have static lighting. Sadly. thus it will be forced to use dynamic lighting.
@JamesG Oh , so that’s where the UDK ProcBuilding come from. I guess the Custom LOD part would be the biggest limitation approaching this from a blueprint angle. And also the part where I cannot have static lighting on blueprint spawned mesh ( and when the building gets regenerated during run-time with possible changes). Yes, I’m the one who asked the same question on your youtube channel 
In fact, I had to find workaround on my blueprint-based system by limiting the static lighting to only the root component. I’m now in a dilemma if I should randomize ground floor shops and forcing them to be dynamic lighting or manually place shop
in order to enjoy static lighting. I very much look forward for a construction script that runs only in Editor that affects save-able content without having to touch code.