The above code does not work. It is not part of overall_header.html BUT should be part of viewtopic.php. I was able to search all the code files and place the code in right place to make my migration successful.
However, all user replies were not mapped to users rather imported as anonymous 🙁 … On the other hand, Topics were successfully mapped to right users. Is there any help I can get in mapping those anonymous users back to right users in bbPress?