Questions AP Workflow Approval but allow edits without restarting the workflow?

Hi -

I have a project accounting client that has a bit of a complex workflow for AP approvals.  

1. AP Clerk enters bill and selects the Project and Project Task of Pending.  Removes hold and releases - this triggers the workflow to start. (pretty normal)

2. AP Doc routes automatically to the Project Manager called out on the Project - (here's the catch) Project Manager needs to CODE the lines of the ACTUAL Project Task (deleting the PENDING) and include the correct Inventory ID, then APPROVE.

3. AP Doc routes to Project Accountant (user defined field on project) and they need to possibly edit the mistakes that the Project Manager made and then Approve.

4. AP Doc routes to Final Account director to approve but they can also edit and then would approve.

So everyone on this workflow needs to be able to edit what the user prior to them did in the system.  

I'm including screenshots of my workflow, it's awesome and working as an approval process but NOT to edit.  Once it is removed from hold or put on hold the workflow starts again. ugh.  

Any ideas would be great, maybe two workflows?