Snapping and Sculpting Landscape on Static Road Meshes

Hi I’m working Simulation Based Car Driving Scene. The Roads are created using 3rd party software with Elevation and Road Markings. Now After Making Roads and Importing FBX in Unreal. Now I want to make terrain around road network. The Issue I need help with is the process of Manually Sculpting Terrain is very Tedious, Does Anyone any landscape creation/terrain creation process. So that Unreal Engine Detect Static Meshes and dont let me sculpt over it. I know it doesn’t happen like that. But It’s very urgent for me.

I have tried making heightmap it has only provided me a base elevation of terrain.