I wonder if there's a rule. From my narrative: I considered using square brackets (probably not standard). And I also considered writing a separate sentence but in the particular spot, it slows down the pace a bit and I wanted to avoid that.
To me it looks a little odd. Why not explain who Ana is in the following sentence, outside the quote?
I think that's not going to work in fictional narrative. I'd suggest (1) making Ana's identity clear before the statement is made, (2) letting the reader be briefly confused, or (3) making her identity clear in the statement itself. I'd vote with letting the reader be briefly confused - there's nothing wrong with letting the reader figure things out rather than handing him all information up front. I'd say that "Rick stopped them by saying..." is a bit too much explanation, too. His words make it clear that he's trying to stop them; the added explanation strikes me as redundant. A possible rewrite, with a blatant hint as to Ana's role, could be: Rick shook his head. "We can't start 'till Ana gets back. She's copying the agenda."
If the speaker is saying it then it's probably better to separate it with commas: Rick stopped them by saying, "We can't start until Ana, the secretary, is here."If he isn't saying it then it doesn't belong in the quotes. You might try something like: Rick stopped them by saying, "We can't start until Ana" -- Ana was the secretary -- "is here."I suspect there ought to be some commas with the quotes though I'm not sure. Safer to move the explanation after the sentence (or get rid of it completely and let the reader find out through the rest of the narrative who Ana is).
Well, it's grammatically sound (if one gets the commas sorted out). I agree it's not particularly good stylistically, which is why I gave some better (in my view) options.
Regarding the use of brackets. I just learned that it is possible to include a note inside quoted material. From grammar.ccc and other places: Within quotations. Emphasis may be added to a word or phrase in a quotation by placing it in italics. When this is done the note [emphasis added] or [italics added] must be inserted in brackets at the end of the quotation (within the quotation marks), or if the emphasis comes at the end of the sentence, in parentheses outside the quotation marks.
That's correct in an academic or technical setting. In creative writing you would only do it if it's supposed to be academic or technical writing. In dialogue it doesn't work.
You could handle this kind of situation like this: Rick stopped them by saying, "We can't start until Ana is here." "Who's Ana?" "She's the secretary. She has the key to the filing cabinet." (Or whatever other reason Ana has to be there.) Or: Rick stopped them by saying, "We can't start until the secretary is here. She has the keys to the filing cabinet." "Okay." The door opened and a young woman entered. "Hello, Ana," Rick said. "Glad you could be here. Do you have the keys?" Obviously, these are just examples. But in both cases, the readers get to know that the secretary has to be there and her name is Ana before they really have to know both pieces of information at once. And the dialogue flows more naturally without having to use clumsy constructions involving brackets. Just a suggestion.