First, Apologies if I picked the wrong forum for this question.

I have a customer, who's brought in a laptop from their recently deceased son.
They asked us to reset the password, which we did. and then we found out that
it has an encrypted home setup.

Unfortunately they have no idea what the password was (which is why we reset it), and they have no idea what the original Encryption Pass phrase is.

At this point, they would like to save the files, in case they stumble across either password, but at the same time they would like the machine reloaded with Windows so they can give it to their daughter.

They don't want to buy another hdd / etc for a correct backup of the system, but would
like the comfort of knowing they have the data, in case the unlikely chance of them finding the password.

What would I backup to be able to later restore the files, should they ever find the password? The Home directory, along with the directories where the encrypted files are (~ 30gb), are there any other files?

Essentially I would like to tar all needed files, so I can format the laptop and load windows as requested. And later use a live cd, or another computer if needed to recover the files, if they figure out the passcodes.

Any Advise?

P.S. Further apologies if this has been answered elsewhere. I couldn't find an answer with my google-fu