I am not aware of an option where updating one workbook will update the second one. However, my quick reply will be to use all dashboards in one workbook so that you update your workbook only once. then save it and make a copy of original and delete graphs/info that doesn't need to be in exec or marketing team in each workbook.
I just wanted to check back with you if solution provided here answered your question or not. If it did, can you please mark as correct answer so that it is cleared from question board that needs to be answered as well as other users in future can benefit from it. If not, please feel free to ask for help. Thank you.