When did Dawn and Joyce find out about Willow/Tara?

Question of the day: When did Joyce and Dawn find out that Willow and Tara were a couple?

In Buffy vs. Dracula, Joyce tells Willow and Tara, "Oh, when you girls are older you'll understand. It's hard to date. Sometimes you just ... feel like giving up on men altogether." Willow and Tara, per the transcript, "sneak little looks at each other and try not to grin."

So…Joyce doesn't know?

But in the very next episode, The Real Me, Dawn write this in her diary: "[Willow and Tara] do spells and stuff, which is so much cooler than slaying. I told Mom one time I wished they'd teach me some of the things they do together. A-and then she got really quiet and made me go upstairs. Huh. I guess her generation isn't cool with witchcraft." The implication is Joyce is well aware that Willow and Tara are a couple, and doesn't like the idea of her own daughter being a lesbian.

But is Dawn aware? She doesn't seem to have considered Willow and Tara's lesbianess as something that her mother her mother wouldn't want her to emulate. Did she not know, or did she just not realize her mother might have such a problem with it?

And if she didn't know - when did she find out?