Work Item in RTC has one embedded workflow concept which is to implement Reviews and Approvals. Escalation is slightly different embedded workflow (or supplementing workflow). Right now I am facing two challenges.

Consider that, Issue is a workitem where we want to implement escalation process. Part of the IT work of the organization is managed by their SI vendor.

1] New Issue is posted by a team member of a vendor
2] Vendor Team Leader (TL) looks at the posted Issue. He takes ownership and finds that this may need to be escalated to the customer. So, he adds his comments and escalates this first to his (Project/Program Management office) PMO.
3] PMO team member of Vendor, after reviewing, aggrees to escalate to the customer. Now PMO team member acts as the sub-owner of the issue, adds his comments and escalates the issue to a customer.
4] Customer member of RTC project reviews and takes proper action or may suggest alternatives. In some cases, he may revert back asking vendor to act on their own. Basically he reverts back with his comments/actions which are recorded in work item as text or state change.
5] In the end, issue is resolved as a result of collaborative action or sometimes it is rejected.

How should one implement such sub-workflows in RTC? In future, it may be necessary to record time of each action and generate certain triggers (well at this point I am ok to run a query and check pending escalations).

Thanks for any suggestion.