Gotdam right on everything you said.When elders in my family had friends over to play cards or whatever, they referred to them by their first names: Harold, Beverly, etc.
I wasn't allowed to do the same. If anything, it was,"Mr. Harold" or "Miss Beverly." And even that's only because I was familiar with them like that.
Shit, I'm old af and STILL put a 'mr.' or 'ms.' on elders' names when face to face.
The young girl should've had enough upbringing to know better in the first place IMO.