Right, been thinking about this.
I totally understand that you don't want to let her cry.
However it sounds like you'd like to move away from co-sleeping (esp if she's not even sleeping but messing about.
What PfftTheMagicDragon suggests sounds like a good option, similar to the approaches in the No-Cry Sleep Solution I think
My only suggestion is that she is an age where she might understand some explanation from you about what is changing. I had somehow assumed dc2 was too young but felt I had to say something to her a few weeks ago as she was being naughty in front of dc1 and I didn't want dc1 to think that I was letting the behaviour go iykwim. So I said "DC2, if you keep throwing that then I'm going to take it away". And she stopped throwing. Sounds ridiculous right? But not like her at all. I didn't say it sternly, just in a quiet serious voice.
So then with bedtime, I've started putting her in the cot and telling her that her sister is going to sleep all night, I'm going to sleep all night, daddy is going to sleep all night and her toys (that she sleeps with) are very tired and want to sleep all night. I tell her that I'll come up in the morning and get her and say "what a clever girl, you slept in your cot all night", etc. I say that I love her all night and am sending her kisses (I know, soppy) and then tell her I love her and leave.
She screams and sobs "mummy mummy no". So I go back one time and say "mummy loves you, but it's sleepy time" or whatever, and then say "I'm going away now and I'm not going to come back until you have had a sleep". I'm in hte lucky position that I feel I can say that and stick to it as I can send dp up to her. If you don't have that luxury, then would your mum be willing to stay the night for a few nights just to try this kind of thing out?
Weirdly, she did cry a bit but went to sleep and the crying sounded really tired. It's like she understood that I wasn't going to go back again. I don't know what I'd have done if she'd really tested me.
I wouldn't recommend myself as a sleep expert anyway, but just wondered if you could find your own way of explaining to your dd the way things are going to be (in a calm, happy voice not a telling off voice at all) and see if she is able to comprehend that as it might make a difference? But maybe something about sleeping in the cot now because she's a big girl but you'll be back to see her?
My apologies if that all sounds ridiculously obvious and you've already tried it.
DC2 started saying "alllll night" when she's playing around with her toys now so something about it is sticking in her mind.
Not sticking enough to guarantee that she does sleep all night mind