From previous experience as an active duty Marine and Marine Civilian, I know the Navy may have their own process for conducting Gate 6/CSB Reviews for ACAT IC programs and this process may have additional requirements. The JCIDs manual provides the following (JCIDS Manual 19 Jan 2012, Enclosure B, page B-5 and B-6) with regard to revisions:
"e. Revisions. Updates to previously validated documents shall be resubmitted to the Gatekeeper for appropriate action in accordance with Enclosure C. If re-accomplishment of staffing and validation is warranted, the staffing path will be determined by the type of document, the scope of the change, and the previously assigned Joint Staffing Designator (JSD) or former Joint Potential Designator (JPD). See Enclosure C for details of JSDs.
(1) For revisions to validated documents, the Gatekeeper forwards them to the appropriate lead FCBs for assessment.
(a) If the lead FCB Chair determines the revision affects one or more Joint endorsements, internal joint staffing is conducted to secure the endorsement.
(b) If the lead FCB Chair determines the revisions warrant revalidation, such as for changes to Key Performance Parameters (KPPs), the submission is treated as a new, un-validated document based on its latest JSD.
(2) A revised validation memorandum is returned to the Sponsor once the revalidation has been completed or the original validation reconfirmed."
From Enclosure C, page C-7:
"5. Processing Sponsor Requests for Changes to Previous Validation
a. For changes to validated ICDs, CDDs, CPDs, or Joint DCRs:
(1) The Sponsor submits the updated document to the KM/DS system as an FCB draft document, and identifies in the "purpose" section that this is a KPP update only and requests direct consideration by the FCB without staffing.
(2) The Lead FCB and the J-8/CAD action officer will evaluate the change and determine if staffing is required.
(3) If additional staffing is required, the change will go through the normal staffing process.
(4) If the update is to the NR-KPP only, the document will be staffed to the C4/Cyber FCB for recertification via the KM/DS system.
(5) If additional staffing is not required, the lead FCB will work with the Sponsor to prepare a briefing for the JROC/JCB to obtain approval.
(6) The lead FCB will schedule the briefing on the JCB and JROC calendars as required."
I do not know of any specific templates for Addendums, Attachments or Enclosures to the JCIDS documents as every Service/Agency does it a little differently. Additionally, I am not sure if a complete rewrite is in order. However, understanding that the Navy's process may have slight variations, if one of the goals of a Gate 6 Review is to complete an "Assessment if Validated Capabilities (CDD) and SDS are met", then at a minimum, a new requirement and/or revised requirement in any form would need to go through the Navy's validation process prior to be implemented.
With regard to a POC, this is what I was able to find via the Defense Acquisition Portal -- POC for JCIDS and the Navy Requirements Management community manager is the Navy JCB rep, OPNAV code N81D (O-7), and the Joint Requirements and Acquisition branch, OPNAV code N810 (O-6), Pentagon Rm 4D453, phone 703.693.9093. I am not sure if the room number/phone number is current, but have included the URL for the JCIDS Manual
(https://dap.dau.mil/policy/Documents/2012/JCIDS Manual 19 Jan 2012.pdf).