Anonymize past feedback to fulfill GDPR requirements

Due to European/German GDPR requirements, we need to anonymize feedback after 3 years latest.
Currently there are only the following options:

- Manually delete single responses (VERY annoying for a a couple hundred responses and on top the history is being lost)

- Delete the survey completely - you’d loose history and progression of past feedback
- Delete the contact(s) completely - not feasible as contacts are still needed.
We need a solution to “unlink” the contact information from the feedback.
Like this we could follow up personally on individual feedback where desired/needed and remove the connection to the survey once it has been followed up on. Like this we could still keep history and progression of feedback.