Hello Mathew,
You can do one more thing to avoid appearance of the Functional locations in the structure list.
Remove the Superior Functional locations from the functional locations which you dont want to be appear in the Structure list.But keep in mind that the sub functional locations will also not appear in the structure for which you removed the superior functional location.
Later on you can put deletion flag.I will suggest not to do the frequent archieve.
Regards
Kavvya