This is a tough one. I am in the same boat with my soon to be 23mo old son. He tells me when he does peepee in his diaper and every night when he gets in the tub I ask him if he has to go before I turn the water on and he says yes and then goes. He also tells me when he does poopies in his diaper. He has told me that he wants to sit on the potty. I have sat him on it. Immediately he gets nervous and has to get off. So, we haven't gotten quite as far as you but I know he wants to go. People have told me that the best thing to do for little boys is let them run around outside with out a diaper and teach them to aim at a tree. We tried that once and there were kids playing so he decided he wanted to play instead.
I was thinking about getting the pull ups that have the "cool alert" so the child knows that something is different and they feel something different when they go unlike when they are wearing a diaper (unless it is totally saturated.). I only have one child so it helps me when I see that others are having the same problem. If your daughter likes to practice that is a good thing. I have heard that it is harder to train little girls than it is to train little boys. (My sister had a very difficult time with my neice who turned 4 in April and potty trained right before her bday, she would do the same thing that your daughter is doing.)
I don't know if there is really an answer to this one. But if she wants to sit on the potty and isn't afraid that is wonderful. I guess I have to say since I witnessed it with my neice, that when she is sitting on the potty and is really ready she will go while she is sitting there. Try M&M's as a treat (that is my plan). And let her know that when she does go she will really be able to "wipe" the pee pee or poopies away.
Good Luck and if you get any really great advice, I would love it if you could share it with me. I am a single mom and my son goes with my ex husb on sat night to sundays. So he has to end up doing the same thing at 4 houses...... Not going to be an easy one!!!
L. :)