Two comments here:
- We have recently released the Project Conversation feature, which in future will be extended to linguists as well. So they'll be able to send messages more easily to the Project Manager
- Trados Accelerate (the next offering up from Team), supports a more comprehensive "Vendor module", which includes Vendor Quote Review by the Vendor, including modifying the Due date for delivery.
As the Project Conversations feature will support the use case above, we are unlikely to implement a specific option for this.