Ockham23, Thank you I got the picture now.
Only I wasn't pepared what to reply if I should overwrite or not.

I first tried to overwrit all files.
Well, I ended up with a faulty system; a lot of things not working anymore.

I started the whole sequence again and this time I didn't overwirte.
The new persistent home is now 125 MB, while the old one was 124 MB, so I presume all old data is added to the new one.

In any case, I did a suggestion at the proper place, to have a one click procedure, with just one question: how much to increase/decrease.
That would be much easier.