Is there a simple way to override a #define such as SERIAL1_RX_BUFFER_SIZE found in serial1.c, from a project level rather than within the core files? It just feels wrong to edit core files when I only want the change for one build not all builds.

If I insert this code at the top of my ino file, it doesn't work because the core has already been processed.
Code:
#ifndef SERIAL1_RX_BUFFER_SIZE
  #define SERIAL1_RX_BUFFER_SIZE 512
#endif
If I could get the pre-processor to start from the ino file then proceed as normal I could tweak the core on a project by project basis. Nice ;-)

Is this possible?