I'm sorry I think I've run you in circles here.
If I'm understanding you correctly what you want to do is place a bunch of smaller terrains in UDK but keep their textures aligned so you don't have seams?
If that's correct you may be able to use a World Position
node in your material to keep the textures aligned between the different terrains. Here's a tutorial
about it. I haven't ever used this technique with terrains though so I'm not 100% sure it'll work.
So many terrains might still be bad for performance though. You might be better off using smaller displacement textures along with Super Masks
and tiling diffuse and normal map textures get more detail onto your terrain.
I personally like to use static meshes in UDK rather than actual terrain. It allows you to have more control over the "terrain's" mesh and also use vertex color based blended materials like this one
to achieve very crisp details. You can read more about such materials in The Snow and Ice of Uncharted2? thread
if you're interested.
I hope that helps.