Can a Scene have more then 1 terrain?

I want to make a scene with 9 terrains visible at the same time like this…

Each “X” is one terrain.
X X X
X X X
X X X

Sure, go for it.

–Eric

Can I use the smoothing brush to “sew” the seams together? Or does that brush not cross terrain boundaries?

The brush doesn’t cross terrain boundaries, even if you have multiple terrains selected.