Thank you Samik for this response.
Are you aware of any integration to MS Project, which is what this Client is using, in relation to Proposed ETC.
I have manually configured the Proposed ETC to push it via the MSP Mapping. The PM can now see it in MSP now, and can then determine what they would like to do with it manually (ie update the ETC manually, and then blank out the Proposed ETC).
In addition, I have also configured a custom attribute Assignee Comment, which was pushed to the Organizer - Task via the Assignments objects, so the Resource can provide additional information back to the PM. This is also being pushed via MSP Mapping.
Finally, I also developed a custom Portlet, based on Pending Estimates Review so that when the PM logs into Clarity, they have easy access to this data and can manually decide what to do with it.