This will seem simple and harsh maybe--funny? But take the bed away. Put down one of those plastic water floats that you can blow up. Cover it with a sheet.
That way when she pees, you can wash the sheet, hose down the bed, and not get so excited. You can tell her when she gets potty trained at night again, she can have her bed back. Be very nice and calm.
Don't get mad, or condescending. Don't ask for explanations--just pretend it doesn't matter. Be joyful and nice to her in other areas.
She will probably try to provoke you somewhere else, because she is in a real power struggle with you. You need to stay calm and not respond. Very Hard To Do. (I've Been There!)
If she throws her toys pick them up and put them away--don't give them up--don't say a word.
If she has a temper tantrum, put her in her room, and shut the door, and walk a way. If she comes out put her back it. Get your husband to back you up.
You might have to take everything out of her room so she is in there by her self and is really miserable.
This really needs to be resolved (even if you need to call super nanny) before the new one comes, because she will be sooo mad then. She is a powerful personality.
I think you should put that power to work.. in swimming, ballet, gymnastics, something that wears her out. Two or three times a week. Do you have a climbing gym outside your house?
Does she have regular play dates?
I've read some of the emails and I would like to insert a note of gentleness. There must be firmness and gentleness I think with your daughter.
I will tell you a story.
I use to teach 1st grade in a area that had some low economic houses. One boy was a problem. He was messy, smelly, didn't do his work, and left out of his peer activities. And I frankly didn't like helping him. I have this philosophy that a circle always has room for one more. So the class was having a group hug and there he stood, left out. I put my arm out to invite him in and he smiled, "me?" In he came, smelling bad. But he was in the group.
Hi performance improved--not a lot. But I liked him more, and I remember him.
Gentleness and acceptance, with firmness. Put her in sports to wear her out---that's what I did with my strong willed daughter. Six days a week, straight A student in Gifted program. She was to tired to fight.