Use this quick trick to merge your GoldFynch tags:
Step 1. Navigate to the 'Tags' view by clicking on the button in the left navigation panel

Step 2. Click on the '...' button against the tag you wish to remove and whose files you wish to assign a different tag to
Step 3. Rename the tag with a prefix, and click on the 'Save' button

Step 4. Click on the renamed tag. This will display all files that have the tag in the 'Search' view

Step 5. Assign the correct tag to all the files:
- Check the 'select all' checkbox
- Click on the 'Tag' button in the right action pane

Step 6. Assign the tag you want to merge your earlier tag into

Step 7. Navigate back to the 'Tags' view and delete the original tag (that you assigned the prefix to)

To learn more about tagging files in GoldFynch, check out the GoldFynch Manual.