Do you disclose NK isn’t yours?

Okay so I stumbled upon a post here that talked about how someone happily gives up that information. When and how are you suppose to say NK is not yours? I’m not saying I ever say she is mine, but I definitely don’t offer up that information. There has only been one time I have told someone I met on an outing that she’s my NK. In that situation, a mom was with her daughter near us and said, “Isn’t that mom’s baby so cute!” And then followed it up with “at least I think that’s her mom”. I’m 20F so I do look young. I was on the swings right next to them so I said I’m her nanny but she is so cute! Otherwise, if someone compliments the baby, I just agree or say a quick thanks. When I’m at play cafes and such, I never offer it up but no one asks?

Also, my older sister worked for a family that wanted her to say she was the mom because she viewed people knowing my sister was the nanny as unsafe. Not sure why? Maybe because they could think she wouldn’t pay as much attention, not sure.

What is normal and what does everyone else do?