As I mentioned yesterday, there was a family get together today. This was something that I had been anticipating for a few weeks, as it was the first time that I'd seen my sister-in-law since I went en femme to the op shop that her mother (I'll call her E for convenience) volunteers at.
Given that nothing was said by my sister-in-law about E recognising me at the shop, it's almost certain that E has said nothing to her about it. There's still a remote chance that E recognised me but chose not to say anything, but I don't really think that that is her style.
For now, I'm thinking that it's probably more likely that she didn't recognise me than that she did. A lack of comment doesn't prove anything either way, but certainly shifts the odds towards probably not. :)