I've been trying to follow the thread, and I'm not sure the upgrade process to Mountain Lion, which is through the Mac App Store only, has been clearly communicated in all the discussion of partitioning, TM backup & cloning of Lion and Mountain Lion. There's a definitive progression in the upgrade procedure...
Purchasing Lion or MtLion from the App Store entitles you to download and run an installer for that version of the OS.
The downloaded installer will begin running as soon as it's downloaded, but you can interrupt it at any time. (For me, it was a four-hour download, followed by a half-hour install, ending with a restart.)
There is a dialog that pops up after the download but before the install. You can cancel the install at that point, squirrel away a copy of the installer, and then relaunch the installer to do the install. You don't
have to lose your copy of the installer.
The squirreled-away copy of the installer can be used to reinstall the OS, or to install it on another partition or on another machine that you control. This spares you the four-hour (depending on your internet bandwidth) re-download.
The installer can also be re-downloaded at any time from the App Store, by going to the "Purchases" tab and clicking the "Download" button next to the purchase.
The copy of MtLion she "purchases" for free through the Up-To-Date program counts as a purchase. (I bought Lion the same way a year ago, and it's still showing up on my Purchases list, even though I'm on MtLion.)
I don't know whether App Store will show the copy of Lion that came pre-installed, because pre-installed does not necessarily count as purchased. (The firmware on her computer remembers it came with Lion and therefore carries a license for it. Pre-installed does mean licensed.) The 10.7.4 Combo Updater is still available (
http://support.apple.com/kb/DL1524) from Apple. The Combo Updater has enough information that it
could re-install on a blank drive, but I don't know if it
will. It may accept the firmware's assurance of a license, or it may not.
In any event she can get back to Lion using either TM or SD. And isn't likely to need to.
