How to add an edition from an ISO into another

[Jack Mcslay]

I'm trying to have a single image with all Windows 7 editions but I can't figure out how to add another edition to an existing ISO, there is a guide on the NTLite but it's very vague and poorly explained and I can't get past exporting an edition into an isolated image.

 

[Hellbovine]

There's a ton of threads on this topic--to do a more advanced search of the forums copy/paste these examples into Google:

AIO site:NTLite.com
Multiple+Edition site:NTLite.com

Here's official documentation by Nuhi (link).
Here's a recent thread with a guide from Garlin (link).
Here's an older thread with a guide by George King (link).

The thing I've asked before and haven't found a good answer yet, is why is this needed? I think this is one of those scenarios where people seek a solution they think they need, but there are better alternatives left on the table still. It's also easier, and has less possibilities of issues to just make multiple thumb drives with the specific images you need. Even in an IT scenario you'd want as many machines as possible using the same edition/version/architecture, because anything else is unnecessary extra maintenance, so I don't understand the appeal of AIO stuff. Is there a scenario where this is actually needed?