Am 07.05.2017 um 14:27 schrieb Jonathan Masur:
While we're on the topic, I think it's a good idea to remain the former municipality boundaries with admin_level=10, rather than delete them. In most merged municipalities I know, there is a requirement for example to have an equal representation of older municipality in commisions (<- I do not know the english term), and it is now possible for people to have a former municipality that merged as a "place of origin" (<- I do not know the english term either). This means the former boundaries still somehow "exist", in the hearts of people if not administratively. Consequently the older municipality relation can also be kept with an "admin_level=10". This is not required, but I'd say it's recommanded, it costs nothing to keep them (simply change admin_level) rather than remove them. ..
Naturally it costs something to maintain them, and given there is no way to verify them post merger*, they would simply decay, annoying everybody in the process.
Simon
* with the exception of such which are turned in to "quarters" in larger cities, which even if iffy, I believe there is general agreement to support that if there is a source available.