Ocean around World machine landscape

Hi all.
can somebody explain me is it possible to do that i tryind and wasting already two dayz.

I created a landscape using worldmachine.
grafik

Off course it is not like a plain, has a different heights of vertex.

I want to make a sea coast, little sand beach, like a spawn point of player, using a Water body Ocean.

As I see, I must to add few plains around my Island and merge them in only one landscape together with Island.
i already tried to do that with World Composition but didnt get a result. It cost to much for performance and anyway my main landscape snapping wrong z location.

Maybe i doing absolute fool thing and dont understand the system.
I would appreciate if someone explain me how to realize that idea to make a small generated world with an ocean around. I m just on a beginner steps of UE learning :slight_smile: