How to add the new tile landscape in World Composition

Hello, all!

I have one question. There are similar questions on different “gamedev”sites in internet without answer.
Situation
I have created world in world composition using „Import tiled landscape“. Corresponding heightmaps were created in World Machine. And now I can sculpt this landscapes (4 tiles in my case) seamless.
So now I wont to expand the world and add next tile. And I have the problem.
If I add this new tile using „Import tiled landscape“, I cannot sculpt this seamless.
Of course I can add the next tile by „Add adjacent Landscape Level“, but in this case I cannot use the desired heightmaps and must create the terrain in UE with sculpting.