Secret Chief
Veteran Member
I have to say I've always often used "they" a lot.We've been using it without giving it much
thought in some contexts.
Excerpted...Singular they - Wikipedia
en.wikipedia.org
"Somebody left their umbrella in the office. Could you please let them know where they can get it?"
To use it in reference to specific people seems
new. (It's "seems" because I've not looked into
this history.)