Greetings Sebastian,
If I had the possibility, I'd change my choice of words in my earlier post above from "The hierarchy between functional locations is not inferred from the edit mask." to "The hierarchy between functional locations is not derived from the structure of the functional location label".
As you correctly point out, the superior structure for any new functional location is defaulted / proposed from the structure indicator - and can be altered.
The hierarchical relationship between the subordinate and the superior is modelled "underneath the hood" simply by a reference to the superior functional location in the subordinate functional location.
And that is why the structure indicator can change between the superior and the subordinate - and why the overall relationship between subordinate and superior functional locations remains the same even when alternate labelling is turned on.
thanks to you for prompting a clarification!
Cheers
Andrew