Bad behaviors

If you tell her not to do something all she hears is the thing you don't want so that's what she does.

Ie no hitting.... All they hear is hitting.

Reframe how you say it.

Time to do something... Make it fun.
Who can win?
Can the toothbrush play in your mouth etc.

Simple choices to make them feel in control.

In terms of hating dad give them time solo to build their relationship.

You need to set boundaries with her. Not just tell her not to do something but when she does something she’s not supposed to do there needs to be a consequence. Also limit overstimulating screen time. Sounds like she could also be acting out as a way to get attention. Try to have genuine one on one time with her both you and dad need to do this. She’s saying she doesn’t want to go with dad that is her only option. She has to learn to “tolerate” him as well. Kids at this age want control over everything. Give her options that are acceptable to you so she can feel like she’s having some control.

You didn't ask me for the options but for example
- do you want to run up the stairs or do you want to be carried? She still goes upstairs but feels in control.
- in the morning for example do you want to eat breakfast first or get dressed first?

How old is the little sister?