Additional first name to be added following decree of 17 August 1938 #germany #names

Peter Wollinski

On 17 August 1938, NSDAP decreed that Jewish people with specific "non Jewish" first names had to by 1 January 1939 add either “Israel” or “Sara,” to their given names. 
It is understood that those people who had to add an additional first name had to travel back to the place they were born to register the change. Is this information correct? Did this occur in all cases or could the affected people just send a form to the particular registry?
What about those people who were born in Prussia prior to WW1 and migrated to say Berlin after WW1 but prior to the former Prussian area coming under the sovereignty of Poland. Where did those people have to register their name change in Berlin?  
Your thoughts will be greatly appreciated
Peter Wollinski