The management company(mc) is the problem, or rather the mc's inability to loosen the reins a bit and allow common,common
,adjustments to schedules to be decided by the supervisors on hand.
This should never have become an incident, rarely should have involved any other employee, be they ever so obliging. *
The "overlap" in breaks is a red herring. If a 20(?)minute absence is this crucial there should not be an overlap
. That is just built-in drama fodder.
However this is not your topic. Bad or unhelpful attitudes are difficult to nail in the moment, and difficult to document. Bad conduct is something that can be challenged immediately and firmly. You are becoming. Becoming a very good manager= hard work.
The selfish worker is not the only person in your workplace who puts their self-interest above others. She just flaunts it. So this is a preview of things to come. Arm yourself.
Your job is to fit her in the "team" with all of the angles and extra parts. Good luck.
I am not saying that a quick fix of a trade should never happen, just that it should not be a yoke on the rest of the crew.