And the data saved on that drive gets "scooted" too, I assume.
I guess I misled you. it was just a figure of speech and not really accurate.
It leaves everything associated with the existing OS static where it is already. It doesn’t mess with those partitions at all. It just takes advantage of extra unused space and allocates some of it for itself and it’s own needed partitions. So you do have to have some extra space available for it to steal from the Windows partition that is not being used. It will see what empty space is on your windows data partition and borrow from that. So as long as the data partition is not chocked full it will have no problem doing all that.
So basically when you get done it will actually be two drives. One with Windows and one with Linux. And it will give you a menu at power up to choose which one you want to boot into. If you let it go on it’s own without choosing then it will go to Linux and auto boot as the default OS. Now if you would rather have it boot into Windows as the default OS, there is a simple one line configuration edit in Linux to make it do that instead of Linux as the default auto boot OS.