Multiple Initials and final Sign off on QA document

Please can you assist me with this query on Adobe Acrobat DC. We have a number of QA forms that go through a process of getting initials from the client and the engineer on multiple sequential items and then once the entire activity is completed a final signature from both parties. The process is shown below:

• the engineer starts the process by confirming checks have been undertaken on first few items, then initials the document & submits to client
• the client confirms he has checked these same items by way of initialling them and sending the document back to engineer.
• This leads onto the next set of items on the document and the document goes through the same process as above.
• Once all items on the document have been checked (Initialled) each party will sign off at the bottom and the document is filed.

The problem I have is that after the first run the document is locked and I cannot re-submit for further signatures from the same parties.