Saving all Meshes on a Landscape

Hey,

I want to create a random map while I use prototypes of smaller landscapes. Now I model, for example, 3 types of starting zones (levels) with houses / trees / bushes …

i now put all the objects (houses/trees/bushes) as a child object of the landscape and want to copy them. But only the landscape is copied without the child objects…

so:
How can i save the landscape AND the objects in a variable, so i can create a whole level using this?

thanks