CA Access Gateway parallel upgrade

Products

• CA Single Sign On Secure Proxy Server (SiteMinder)
• CA Single Sign-On

Issue/Introduction

Is there any document available for parallel upgrade of CA Access Gateway?  The goal is to migrate to the latest release without disturbing the existing environment.

The upgrade guide details in-place upgrading, but does not mention parallel upgrade:

https://techdocs.broadcom.com/us/en/symantec-security-software/identity-security/siteminder/12-8/upgrading/in-place-upgrade/upgrade-access-gateway.html

How is a parallel upgrade performed?

Environment

Release: MSPSSO99000-12.8-Single Sign-On-for Business Users-MSP
Component:

Resolution

There is no parallel upgrade available for Access Gateway (formerly Secure Proxy Server).  To achieve the same effect, install a new instance of Access Gateway and then manually transfer the needed settings from the old installation to the new.