What script defines the Waypoints variable referenced in the Behavior Tree?

I can see that the Spawn Points components on the Waypoints game objects have a Group ID of -1 but I don't see how the items with that script and group ID dynamically load into the Behavior Designer variable for Waypoints. I want to dynamically set the waypoints per spawn zone that gets activated and it would be helpful to know what script is handling this so we can do something similar. Please advise.
 
DeathmatchManager.SetupPlayer populates the waypoints at runtime. It does this by looking for a specific ObjectIdentifier and getting the children from that.
 
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