Collaboration at object definition and/or occurence level.

When Viewers want to make a comment to a model, they usually don't comment on the model it self (Its name and so on), but rather the content of the model... the objects within the model).

If Viewers are able to multi-select objects and create a comment on those objects it would allow more granular feedback context.

If you can find a way for Viewers to classify the feedback as pertaining to Object definition or Occurrence (even though they may not understand the concepts ;))

Object definition Example Selecting two functions e.g. "Determine order size" and a later "Approve Order" and giving feed back on these could make it so much easier to communicate "We need to not just approve the order but also the size."

I appreciate that a Change Request pertains to the entire model, but providing a more granular Object context would make feedback easier to understand and preventing the need to explicitly specify the context in free text form. (Some users don't specify that.)

A simple way could be to add Object lookup functionality to the Tagging functionality.. But that may not be so intuitive and needs promoting as a practice.