Forward Declaration of Scoped Variables (Uniform Buffer Objects)

[Kastenfrosch2]

I attach two vertex-shaders to my Program Object

Vertex Shader1:

uniform BlockName{
  int varName;
} scopeName;
 
// ...

in Vertex Shader2, i want to use varName. So i forward declarate it.

uniform int scopeName.varName; // Compile Error: unexpected syntax Error at "."

Edit:
Makes sense, because the compiler doesn't know about scopeName when compiling Shader2.
But how can i use the scoped uniforms in my second Shader? Can i forward declarate or redeclarate the Scope or the Uniform Buffer?

I didn't find anything about it in the Uniform_Buffer_Object specification.
(I use a GeForxe GTX 560 with Driver 296.10)