Have you thought about a Parenting seminar? They are really, really useful when it comes to dealing with nortiness, but also what you can expect from a 4 yo, and it gives you lots of different ways of dealing with the behaviour.
We did the same when
DS was running amok, it gets both parents on the same page with everything, and can give you a bit of strength when you fell you have none.
My advice would be to always maintain consistency, always. It can be wearing at times but you just gotta do it.
There is Positive Parenting and 1 2 3 Magic - highly recommended.
One of DSs FAVE things was to stomp around or slam doors when I was trying to get bubs to sleep. You cant ignore that behaviour and presses all your buttons AT ONCE
GGRRRRAAAAAHHHHHHHHHH!