I am not able to test this today. Will try tomorrow or weekend.
It has something to do with laptops that are not mine. The owner of my local pub has two 8.1 ones he has upgraded to 10 Home but is not happy, wants clean install on both and promised to take quite a nice sum away from my always too big tab if I do it for him. I know both have embedded OEM keys for Home, want to test how it goes.
Went there today to get laptops or at least one, heard from barmaid he's expected to be there late tomorrow and work all weekend. I will of course tell him I am testing something while doing what he asked, don't want to do things like this behind his back, but I am sure he accepts that.
My idea is not very clear even in my own thoughts, I'll tell later how it went and what did I try.