Associating existing potentials with a new CRM Campaign

Associating existing potentials with a new CRM Campaign

Is it possible to add existing potentials to a new campaign? In the Potentials file of my data backup, there is a field called "Campaign Source" that holds the campaign IDs of potentials that have been associated to existing campaigns, but there does not appear to be a way to update this field either through the import feature nor the API. Please advise.