Some questions on maintaining addons with multiple Blender versions I use a special build of Blender made to work with the Octane render plugin.  But I also frequently go into the regular Blender since Octane Blender is sometimes a release behind. What is the best way to maintain my plugins so multiple Blender versions have access?

Currently, I have plugins in each of the installs addons folder.  But I also notice my installed addons (like Flip Fluids, Khronos glTF exporter) also reside in the Windows AppData/Roaming folder. 

When I want to update an addon, what is the most efficient way of doing this?
Do I need to copy the new files into each installs addons directory as well as the AppData/Roaming directory?

Can I delete the addons I want to update from each of the Blender installed script directories and JUST copy them to the AppData/Roaming directory?

Or should I set a custom path where each version of Blender can look for addons?
If I choose a custom path, does Blender still look in its own installed addons directory - first for all the addons that come with Blender and then in the custom path?
Blender saves its config files in a different folder for each version of blender. If your custom build is based on 2.79 then it will read the same config as the standard 2.79 build. The location and layout of config folders is explained here.

To have the same addon available to multiple versions, you need a copy of the addon in each versions config folder. To simplify upgrading you can use links to have each version read the same file contents. Links are also known as shortcuts or aliases. Create a folder for your addons and put your addons there, then create a shortcut in each config folder that you want the addon to be available. This may be easiest if you install the addon for the current version and then make links from that to any older versions you want to use the addon.