Hi Asfan,
Like Angel mentioned, the pivots are usually retained. One think I can think of is to uncheck the ‘Combine Meshes’ bool on UE Import.
I’d also try exporting a simple test in whatever 3D creation tool you are using.
Best-case is that everything imports with expected pivots, but there are some tools with the new Modeling Mode for help with hand-authoring pivots. (Select Mode button in upper left of screen)
Cheers