No, they want to read about all those things in each of your own words, hence why the narrative boxes are included in both the applicant's and the sponsor's applications. If you choose to write "see statement" in those boxes, you each still need to do one of your own covering each question.
You can always choose to add any additional joint statement but there is not much point as you should have covered what immigration wants in your individual statements.
You can always choose to add any additional joint statement but there is not much point as you should have covered what immigration wants in your individual statements.