Modify an environment parameter

Hi

Here is my configuration: I have a project B which is triggered to build when project A finishes to build

My project A use an environment parameter with name "param1". Just for my tests, the project's A build is just a print out of this parameter's value on screen
My project B use an environment parameter with name "param1" . In the same way, it just outputs a parameter value on screen

My question is when I custom-build the project A and I modify the value of param1 how do I modify my param1 value in project B to be the same as in project A? Basically, I want to find the same param1 value in project B after having it modified in project A.