So sorry, cakeslover.
I have a thought about taking your dd to hospital to see her dad.
My brother died suddenly and unexpectedly some years ago. The funeral director asked if any of us would like to see him. I didn't, but dd desperately wanted to; she had witnessed my mum's death only a few weeks before (we had all been with mum when she died). DD is very mature, and haing been at the bedside with mum and gone and viewed her body, she was sure she would be fine.
So dd was taken to see him by her dad and my beother and some other good friends. She was 10, so a lot older than your dd. Moreover, we had had 6 other bereavements in the couple of years leading up to my brother's, so she was 'experienced' for want of a better word.
She regrets it utterly. He had not been made pretty, and it was actually rather frightening. 3 years on she remembers what he was like when he was her lovely uncle, but it took a long time for that horrid picture to fade in favour of the memories of the man she knew.
Another one, concerning me this time. My dad died of cancer over 20 years ago, at home. The last few months he deteriorated badly, and my brothers and I visited at least once a week, generally more. I was over 30, and it took a long time to get those memories out of my head and start remembering him as he had always been.
Have you asked your mum what she thinks? Sometimes it's kinder to leave memories intact and uninterrupted. Your dd is very young.
On the other hand, I can see why you think it might be the right thing to give her a chance to say goodbye. Please don't take offence at this, but the daddy she knows and loves has gone already. I'm so so sorry 