Communication between Process and Subprocess (Call Activity)

Hello, I would like to know how I can model BPM in this situation:

How can I do to trigger a Call activy in the main process while executing a call activy?

I would like the red task “Review proposal” to start the call activy “Review proposal”

Example: The Call Activy “Drafting a contract” will only start when the task “Review proposal” is completed.

Children Process

Father Process

I would like to pass a variable from the process to the sub-process during the execution of the sub-process;

Without ending the Subprocess