We are able to combine two things when two things happen at the same time .Like in this example
She is in the kitchen and she is making coffee.
She is in the kitchen making coffee.
What about if the subjects are different ? . Is it still possible to reduce the sentence 1 to the sentence 2 without changing the meaning and is sentence 2 grammatically correct?
1- Julia was cooking dinner and her brother was reading a book .
2- Julia was cooking dinner her brother reading a book .