In the landscape tool you have to go to the manage tab. There you should somewhere see a button to import another one https://docs.unrealengine/latest/INT/Engine/Landscape/Editing/ManageMode/index.html
In the landscape tool you have to go to the manage tab. There you should somewhere see a button to import another one https://docs.unrealengine/latest/INT/Engine/Landscape/Editing/ManageMode/index.html