D..
You might not like my advice, but I'll give it since you are asking.
Tell her during the day that you aren't going to be allowing her to come in your room anymore during the night and that you aren't going to lay down with her anymore at night. Tell her that she is wearing you out and that everyone in the house needs sleep. She is now a big 4 year old and you are done talking about it.
The first week was a novelty with her brother. That's what's going on. Reality has hit and she is being a drama queen about it in hopes of getting you to let her back in your bed or keep you in her bed. If you want to sleep on your own, you have to demand it and allow her to cry.
Expect her to stay in her room. If doesn't matter if she sleeps in the bed or not - as long as she is in her room, that's what matters. Every time she gets up, walk her back to her room. Don't talk to her. Don't engage. Don't go in the room. You'll have to do it 50 times the first night. Don't give in. Ignore her cries. She will finally be so exhausted that she will go to sleep and not wake back up until morning. Make her get up at the same time, and when she says she is tired, tell her that she had better stay in her own room so that she won't be so tired the next day.
Don't bring up the subject of the bed. Just make it about her room.
I know this is hard. But in a week of 100% consistently taking her back to her room, and not talking to her or putting her in that bed, or having anymore conversations about that bed past the initial one, you'll finally have some semblance of normalcy.
Let her keep the aquarium light on. That's it. Ignore everything else she makes up to get you on her hook.
There you go. Hope you can do it, mom.
Dawn