When importing Participants using a CSV file the system will add all Participants, unless you map a RunSignup Regsitration ID, or a RaceDay Scoring Participant ID. When you select to map one of these fields, the import process will now update matching records with the supplied data, instead of adding new records.

This is very useful if you need to update Participants that are already in the database if you forgot to import a field, or you need to change values en masse from a spreadsheet.

You can use the Participants > Actions > Export to CSV option to create a Spreadsheet including Registration ID and RaceDay Scoring Participant ID, then add in any additional information needed to that spreadsheet, which you can import back into RaceDay Scoring so that that new data is added to the records that match the IDs you have in it.

For instance, if you did not import Teams, you could export the Participant data, add in the Team Name and Team Type for each Participant, remove all columns but the Registration ID column, then import that spreadsheet to update all records with their correct Teams. 

When importing, make sure to map the RunSignup Registration ID, and the data you want to update:

When processing the import, it will let you know that it is going to update instead of add records: