Win7 Pro SP1 64bit: Slipstream - Advice/Info Please

[TearsInTheRain]

I wanted a backup of my Windows 7 Pro SP1 64bit disc and decided this would be a good time to do that and slipstream in the April 2016 Convenience Update Rollup at the same time. So I downloaded that version using the tool here and everything seemed OK until I actually tried to mount the image using Command Prompt, required to be able to add the two necessary update files to the ISO image.

When I used cmd to display the product ID it just reports as "Windows 7" and no particular version ie. HB, HP, PRO or ULTIMATE. When you mount the ISO image using, as an example:-

Dism /Mount-WIM /WimFile:C:\Win7SP1ISO\sources\install.wim /Name:"Windows 7" /MountDir:C:\Win7SP1ISO\offline

cmd reports an error and that the file cannot be found in the install.wim.

That is not strictly true; there is a Windows 7 OS in that location but it is all open in the root of the directory (see 1st attachment). I thought this was some download error so I retried: same thing, same result. So next I checked my original discs and found what should be in the "install.wim" (see 2nd attachment).

In each of those numbered folders are the Win 7 OS, presumably HB, HP, PRO and ULTIMATE.

Now there may be a good reason why the download "install.wim"  comes like this; I note there is a Recovery folder and bootmgr and BOOTSECT.BAK files which are not included on the original discs I have. Maybe, like this, Win7 Pro SP1 64bit will install as OS without problems but for the purpose described, creating a slipstreamed backup disc, whatever path name I use for the slipstream process I'm getting the same error message.

I do find it odd there is any difference between the content of the "install.wim" on my original discs and the download - I'm guessing if I put those loose Win7 folders/files into a folder name "3" the process would correctly ID the version and the path would be recognised. But having to do that suggests someone has modfied that OS install folder for some reason or made a mistake, perhaps copying in those files direct from a working PC.

If someone here can explain why it is packed in this way and what path I have to put in to mount it for slipstreaming purposes to create either a universal Win7 OS install disc or just a particular version I'd be grateful.