We don't have this feature at this time, unfortunately.
We understand that collaborating with a lot of team members on Orders can get difficult, especially when there's so much happening at one time. In the future we hope to offer more control and tracking on activity in your Showroom.
For the time being, our only recommendation is to use Order Tags if you wish to add more immediately visible info on Orders.
If you are interested in seeing automatic email notifications for Seller Order Activity in the future, please contact Support.