If I am understanding what you are asking, the question comes down to not only reworking the phycial loop, but also cleaning out the old tags/PCU Nodes from the system as well.
In general, most of the folks that I have worked with have left the hardware in place, turned off the power in the PCUs and removed the tags from the consoles for those PCUs, which I did not see listed in your description, and remove the nodes from the Composer project. However, physically removing the hardware is fine as well.
You will want to delete the tags from the console tag lists and rework your graphics as needed so that you do not call up data from the removed PCUs, just to clean things up. Also, removing the tags will eliminate the CIU from marking them offline.
It would also be recommended to remove any AI/L (FC 26) and DI/L (FC 42) and AI/CNet (FC 121) and DI/CNet (FC 122) function blocks from the controller module configurations in the remaining PCUs that were referencing the PCUs being removed.
If you have the product, the DBDOC Utility from G. Michaels Consulting LTD (www.gmcl.com) is something that would be a very effective tool for identifying any and all of the relationships between the PCUs being removed, the remaining PCUs, the Console Tag List(s) and the Console Displays. This product will be very useful and time saving in cleaning up your configurations, tag lists and graphics when removing these PCUs. If you do not own the product, you should reach out to them and discuss your application as they would be happy to provide you with a demo to show you how this might be of help. They are also in Alberta, based in Edmonton, so they would probably be happy to come in and meet with you. We have had customers use DBDOC in just these types of applications with great success.
Finally, following the cleanup of the configurations and taglist(s) and graphics in your system, there is one final set of things that I am about 99% certain would also be recommended, if you are "cleaning things up" with your system like you described. Now assuming that these changes will be done during an outage or in a situation that would permit, after the updated configurations, taglists and graphics have been installed on to your system, I believe that you will want to:
- Reset the console CIUs to clear those tags from the CIU's point table
- Reset the CIUs for any applications, like OPC servers or Historian Interfaces, that may have also been referencing the removed PCU tags/exception reporting blocks
- Reset both NIS/NPM modules at the same time in each of the remaining PCUs to have them rebuild their point tables and eliminate any remnants of points that may have been communicated between these PCUs and the removed PCUs.
At present, these are all of the things that I can think of that we have done or seen done in the past when updates like you are discussing have been done to an INFI 90/Symphony-Harmony System.