Edit sub-task in same operation as the main task(s)

As a Development leader/(ScrumMaster)/Testleader, I want to be able to edit sub-tasks at the same time as I change the main-task. At least on these fields (and custom fields also):

• Priority
• Release version
• deadline
• Comment
• Released date

TEST
Use a filter with maintasks only. (Some of the main-tasks containing subtasks). Goto Massupdate, and tick off a few tasks. Somewhere in this dialog it should be a field to tick off Update also sub-tasks, change for instance [Release version] this shall be updated on all tasks and connected sub-tasks )