Hi,
For this what u can do is:
Let's say you have 2 bpmn -1&2
So in bpmn1, u need to throw an intermediate signal and let's say we give the signal name as throw and you can pass whatever data u wanna pass too.
Then in bpmn 2 you define a start signal and give it the same name "throw" and capture whatever output you were throwing.
Now to go back to bpmn 1, similarly in this case u can define an end signal with signal name catch & the data, then go back to bpmn1 and define a catch intermediate signal with same name.
Main thing is that the signal name should be same.