1) how do you propose to make the linker handle it
2) if you have a solution for 1) then write some assembler routines that convert a call to Xralph (compiler a) to a call to ralphX (compiler b).

Some compilers push variables on the stack, some put them in registers a throrough analysis of the two compilers will be required (e.g. what is the compilers 'rule' for registers preserved when a function is called)

Erik