Thanks for the reply. The video didnt have merging of paint objects. Usually the paint objects are created when individually baking sculpted objects in 3d coat. When export as an obj in 3d coat, Unreal game engine would detect the import of the obj with these paint objects belonging to individual static meshes.
For example: If i baked three retopo meshes and three paint objects would appear in 3d coat. After exporting as a single object, Unreal will detect the import with three static meshes.
Unreal has a functionality of merging them back together as a single mesh. But i am looking for 3d coat solution.