Arduino Board txt ediditing or replacement Question

I am using files from the V.1 erra for both Marlin and Audrino IDE.
Any later compliler Pukes while verifying. My Question is about Board.txt. 
If I place A library in my sketch folder will IDE use what is in That folder to
compile ? Do I need to add a recipe to Board.txt (SketchBook) for mega2650.Board.Build= 
and what name do I use? I am trying not to Bork anything here."SEE ATTACHED library"


###############################
mega2560.build.mcu=atmega2560
mega2560.build.f_cpu=16000000L
mega2560.build.core=arduino
mega2560.build.variant=standard
????

rambo.zip (67.9 KB)