How fake function framework can be used when 2 processes are involved in C/C++?

I am having some C code (my test object) which is interacting with some external library. To do some component testing I have written a stub for external library. I am using google test framework to write test cases. I am seding some signals between my test object and google tests which means I am having 2 processes. 1 for google test and 1 for my test object. Everything works fine.

Now instead of using stubbed library I want to use Fake Function Framework (fff.h) which provides auto generated stubbes. I know how to generate stubbes but the problem is that it will work if we have a single process but I want to use it for multiple processes. Is there any way to do this ?