UEFN stands for Unreal Editor for Fortnite
Choose Modeling in Selection mode (top left Corner) in UE
Edit imported shaped polygonL PolyEdit tab → PolyGroup Edit → e.g. Inset Edge Loop
To duplicate meshes while keep the original mesh not changed:
Create tab → Duplicate → Accepted (a new mesh is created in browser, it can be edited. If just Ctrl +D in scene, they all will be changed when either 1 is edited)
Imported meshes merging (if it’s fragmented meshes), orienting and pivot setting:
Select all mesh need to combine → Create → Merge
Orient, scale the mesh in scene correctly → Transform → Bake Transfrom
Transform → Edit Pivot → drag the pivot to where I want:
P.S.
Good habit to inspect meshes modeling structure/point cloud/polygon:
Attribute (e.g below of red line means those are 2 pieces, not connected, just merged)
To make it into 1 piece:
MEshOps tab → Weld