The .H contains:

#DEFINE ONEKB 1024

If your code use the constant ONEKB as:

IF THIS.FileSize > ONEKB
ENDIF

Then, once complied, it is saved as:

IF THIS.FileSize > 1024
ENDIF

If the subclass contains:

IF THIS.FileSize > ONEKB +1
ENDIF

Do I need to include the .h in the subclass? Yes.

If the subclass contains no code, do I need to include the .h in the subclass? No.

The .H file is not subclassed. It is only used by the precompiler.

HTH