How to correct the parents of false organized labels

[Pharoah]

After my first base and automatic import
my Label "Asien" has the parent "London" instead of "Ausland".
What is the best way to correct this. (18.484 pictures)
1) Change the parent of "Asien" from "London" to "Ausland" in the detail panel?
and then?
Auto synchronize metadata, or save metadata to file, or?

[gcoupe]

Well, I don't know whether it's the "best" way, but the simplest way I've found is to simply Right-click on the label, and choose "Relocate this label". Start typing out the desired Parent label in the search box that appears (e.g. Au) until you see the Parent label come up in the list of results. Choose that, and the label will be relocated, and if you have auto-synchronize switched on (as I have), all your images with that label will have their metadata updated.