Update Activity status for email completed via CRM inbox

This seems to be to be a feature omission from a fully integrated CRM-BCM (it's easier to write than SAP Contact Center) solution.

Our scenario is thus:

We are using the ERMS push, where email workitems are pushed to an advisor by BCM. However, we have introduced a standard feature to alert the user to other incomplete emails from the same email address, and to direct the user to the inbox to complete them from there.

There is currently no mechanism that I can see whereby completing a mail from the inbox can update the corresponding activity item (linked by ERMS CON_ID and workflow workitem ID) to "Handled" status. Even a hack where we in the background update the database would require a CEM restart.

Does anyone have any thoughts on this, and how would we go about suggesting this as a feature request to SAP?