Add values to a list (text) field that stores already content I want to add additional values to a list field, that stores already content.

In the field configuration i get of course:


  There is data for this field in the database. The field settings can no longer be changed.


Is it acceptable to ignore this message, add my values via the textfield without touching the current ones and save the field?
Yes, that message is very unfortunate. Ignore it.

Adding options is perfectly fine. Removing unused options is fine too. If you try to remove options that are still used, it will prevent you from doing so.