display related field meta on backend

Hi -

I'm building a version of a scheduling app and I am using a total of 4 CPTs...

1. Events => related to Venues reciprocal, Assignments reciprocal
2. Venues => related to Events reciprocal, Assignments reciprocal
3. Employees (both a CPT and User Role) => related to Events reciprocal, Assignments reciprocal
4. Assignments (all other CPTs relate here) => this is where I want to build the schedule of Employees for Events

My question is:

If I add post fields for Events, how can I pull the rest of the custom meta associated with Events into the Assignments form?

We will have dozens of Events available to pick from for each schedule, so I'm hoping that when I select an Event, that the related info dynamically populates into the form. And then if I add a second Post field for Employees, I want to create records that associate an Employee with a given Event.

I don't see a way to do that in the Post field settings, and I don't see instructions in the KB.

Thoughts?