Use parameter from one BP in another

I have a BP that references other BP’s. BP A has properties that reference BP B. In my event graphs on BP A, I have a variable that I need to reference on BP B. How can I do that? Essentially, I have a RNG on the main BP that I need to make accessible from the BP’s that are called as properties. An example of this is the Spawn in Location Effect for the Supply Crates. I need to change something for the BP that is referenced by the Supply Crate Drop. I can do so in the event for the Emitter, but how do I reference a integer variable that I declared on the Supply Crate for example?