Make questionnaire editable after linked to a source

For some our questionnaire fields, another application is the source. I can upload a CSV of course with the updated information (very cumbersome process, but that is another thing). However, if I link some of the questionnaire fields to a field in the CSV, these fields become read-only and I can no longer edit those fields manually when needed. Is this standard and can this be changed? I would like to have the option to override the values when needed. The source has a different owner and use case for the data, so changing the data there is not always useful.