The Reverse Merge Translation Procedure is for Merging Translations from BoTran Translation Files that have a Default Language different than your master dictionary.  In this case, I have English as the default for my Master Dictionary.

Finnish is the default language for the Language file I am importing or Merging from.  I would therefore Map "Default" into the "Map 1" drop down to use that column from the source file to put into the "Map 2" column, which is "Lang5" in the destination file.  Then I would set "Map Default Language Column" to "Lang2" in the Source file, as that is the column that has the English Translation in it that I need for the Default Language for the destination file.  I check the "Add If New" because I want to store all translations in my Master Translation Language File for use in later translation files for new apps.