If you actually confront her about it (gently), I bet she’d be too embarrassed to keep doing what she’s doing. If you told her in a less kind way, she’d be less likely to feel obliged to stop.
You can’t realistically expect anyone to know they’re doing something wrong if they’re not told (especially since you yourself will eventually have blind spots, as will anyone, since the human experience is way too broad a thing for anyone to naturally be able to identify with enough points of view to thrive in every situation they’d like to). Also, doing the behavior might be what they consider to be already having tested whether the behavior is unacceptable or not, and when that’s their method, they’ll just keep doing it unless told not to.
You should also make a point of asking yourself if you’re doing something wrong without knowing it, and that’s what’s inspiring her actions. After all, if it’s so easy for what she’s doing to be offensive but for her to be unaware of it, you should wonder if it’s really that hard for you to do the same, even if it seems like you already have thought about it. I don’t mean that as an insult, I just mean that it’s a question everyone should make a point of asking themselves before looking to others when something goes wrong. The only truly reliable way to be sure what you’re doing isn’t the thing that’s wrong is asking someone else, but we forget that sometimes.
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It looks like proprietary knowledge may be at risk if you keep letting her copy you, which is a better reason to complain than just her copying you in general. About the latter type of copying, though:
That kind of thing annoys me too, but I can’t really find a reason at the end of the day why it actually is good to be annoyed at being ripped off. What I would do with the knowledge of having been recognized as the originator of a certain idea would pretty much be think to myself “good, they know”, but that’s about it. There’s nothing constructive about it. I know that there’s a such thing as being unable to control that response to being copied, though, or at least not having the means at your disposal to make yourself feel a different way, at least without serious work, so I’m not being judgmental.
And at the same time i know what it’s like to have worth and feel marginalized, it sucks. Copying you could be a desperate attempt to cope with such feelings. Could any of that maybe be how your friend feels? You should ask.
When confronting her, you should make a point of assuming that what she’s doing has a good reason and that any harm done is unintentional, and to really make her feel properly respected and treated fairly, that you’ve in ways failed as a friend for not getting what was going on sooner (which is technically true, but I can see why it’d feel unfair for you to have to say it about yourself).
Again, none of this is meant to be insulting to you. My recommendations usually involve introspection, because I know it’s usually a thing that’s underused. And not just underused, but thought to be in use when it’s not. I don’t assume I myself wouldn’t still be capable of doing such a thing, so I’m not talking down to you.
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I don’t assume that you haven’t already thought of my advice or that I must know better than you. I put down what I put down on the off chance it might help, but I don’t, of course, know the situation as well as you.