It also gets interesting with proper names. It's perfectly legitimate to transliterate "Herr Schröder" to "Herr Schroeder" (and if you don't have ö at your disp

It also gets interesting with proper names. It's perfectly legitimate to transliterate "Herr Schröder" to "Herr Schroeder" (and if you don't have ö at your disposal you have to), but a proper name that starts out with the transliteration, like "Dr. Oetker" can usually not be transliterated to "ö". In some cases that might be because the "oe" was never an "ö" in this case, even if people might have shifted to pronouncing it that way. But in other cases I imagine that it was intended and did start out as an "ö" sound, but people just decided to write the name with "oe". (Same with the other Umlauts.)