Mapping Events to Places during Import

We have a CSV file that contains data for both events and venues (places). I’m going to import this once to create all the places, then run it again to import all the events (obviously copying the required columns to the correct import templates).

Question is, how do I map the events to the places previously created?

Each line of the CSV contains all data for the event and the place associated with it, including unique place IDs, lat/long and zip codes, but I can’t see any way to perform any kind of function or mapping using GD’s import tool?

I looked at using WP All Import but because GD saves data for the custom post types to its own tables instead of the post_meta table it doesn’t find the custom fields. That said, it does allow you to run functions so could conceivably run a function to map all the data but it would be slow.

37,000 lines in total, I think I’ll test with just the first 5.