Hi Ricky,
You can fulfill your requirement using the BadI - ORDER_SAVE. As per your requirement, the user will change the status and will then press the SAVE to save the Document. You can check if your requirement is fulfilled by checking the status of the tasks.
This will be a clean approach with minimal code changes. You can also do the same in the Web UI but in that case you need to enhance the component and then need to do BOL Programming to achieve the requirement.
Let me know if you need any more input regarding the code logic implementation.
Hope this helps.
Thanks,
Samantak.