I would consider the tracks as interchange tracks. So at the beginning of your session whatever track has cars, those are the inbound cars. The empty track is for outbound.
Or you could designate one track of the 4 as the interchange track. Then you start each session pulling the cars on that track and sorting them using the other 3 tracks as your yard. At the end of the session you put the outbound cars on the interchange track for the “other” railroad. In between sessions you could change those cars out with off layout cars to get some variety and use all of your cars.
Obviously the “two” Yards are actually a single yard, but you should designate two trasts as Westridge, and two tracks as Eqstbrook. In between them there wants to be a Through Trak, Just Incase Amtrak’s Empire Builder should pass through.
The straight line arrangement makes it easier to see what is happening.
There is a lot of variation in how people define a fiddle yard. It can be a spot on your layout where you manually take cars off and on and make up a train. It can also be an extension of your layout where tracks are arranged vertically, horizontally or radially and connect to your layout.
Cassettes and sector plates are other terms used to describe this arrangement.
It is a form of staging, however when I see people refer to staging here in the US, I think of a very large multitrack yard, which may or may not be hidden from view of the normal operating layout.