This occurred to me last night. I’m filipino and I have real aunts and uncles but it’s also tradition to call close elders who aren’t necessarily your aunts and uncles, auntie or uncle as a sign of respect. I wonder if it’s the same in FT land. The guard called Belle’s father sir but that could also be a sign of respect.
Either Gaston was actually knighted or noble enough that people referred to him as ‘sir.’ Just a thought.