If you have permission to add an additional/special reviewer to a proposal en-route to Signing Officials, you can add as many as required, while the proposal is at your stop (or if you have this permission: SPO + UD). For example:
3. Then back in the Summary/Submit screen, Cindy (or whoever added Chip) MUST click the [Send Adhoc] button to insert Chip into the Route Log and notify him there's a proposal for him to review+approve.
4. Similar to two Chairs getting a proposal at the same time, Chip will be inserted at the same approval level as Cindy. In other words, the proposal will not proceed to the next stop (Bonnie) until both Cindy and Chip have approved it.