Feature Request - Import Lead source information from CSV files

It would be great if Ontraport allowed CSV files to be imported and matched with Lead information such as 'first lead source' and 'first medium'. 

We've just hosted a physical roundtable event, and given the Event is a marketing initiative, and the first time we've interacted with these leads, I'd like to be marked in this way. Currently, there is no option to do this upon import contact matching in Ontraport. Instead I have to manually update each lead. Not such a problem with a list of 30 x contacts, but an issue if I host a larger event.