I try to avoid punishment but am happy to dole out consequences if I think they are merited.
I think with a sleepover situation I would have just said the first one - no more sleepovers if you have homework, unless the homework can be done first. Because she's proved that she's not mature enough to take the responsibility of the homework seriously after the excitement/no sleep of a sleepover. And perhaps review this when she's older and has proved in other ways that she is responsible about homework.
I think I would have ignored the "don't care" because actually it doesn't matter if she cares or not now, what you've learned from this experience is that she isn't responsible enough about homework to take charge of it in this manner yet. Perhaps if you felt strongly about the homework and/or wanted to make an extra point then extending it to missing brownies in order to make time for the homework makes sense too, but again I would have ignored the "don't care" about that too because it's not about caring, it's about making time for the homework and getting her to think about when she can fit it in. And in fact, it may well be that when it comes to brownies night or someone invites her for a sleepover and she isn't allowed to go, she will think about the reasons why you're making her stay home to do homework instead, and perhaps it will make her more inclined to get the homework out of the way first. She does care - she doesn't want YOU to know that. IMO it doesn't help to keep trying to gain that reaction which shows that they're upset about it - think about your consequence, if you're happy with it teaching something or preventing the situation from happening again, then that's enough. Don't engage with the battle, because you'll end up threatening (and having to carry through!) something that's totally out of proportion to the crime, which just makes her resent you. (Even though actually it's her reaction which has pushed you to this reaction - argh! Aren't pre-teens great??)
Of course this is purely theoretical
- DS isn't homework or sleepover age yet, so it's not something I've come across in real life but this is how I'd handle it, hopefully, if I was thinking it through, in an ideal situation etc.
The one we have had which is similar is that if DS plays any kind of electronic game before bed he ends up really hyped up and it's difficult to get him off it when it's bedtime, so I've banned them from 6pm onwards. The first time I said this he couldn't have cared less, he said he didn't want to play them anyway, etc etc. But every now and again he asks and I say no and remind him we don't play computer games before bedtime, only in the day. And sometimes he whines and moans that it's not fair and if I explain the reasons he promises to go to bed nicely etc, but I know it won't happen - so it stays the rule.