assigning users to a level at time of import of a CSV


We are currently in the process of building a site which will have circa 20k users which will be getting imported all at once. The site’s purpose is for a series of events which all have either a unique venue and date, or it could be in some occasions the same venue on multiple dates

I know how to assign and set up membership / access levels to subscribers and so on once a user has been imported, but my question is at the time of importing users from a CSV, is there an easy way to assign which level they will automatically join?

At present we are importing a list of data for the users from a CSV file and assigning this to their WP user META which we can then use to prepopulate forms, content they can view and so on.

My query is that I am unsure if there is a particular field that can be added to our CSV file which would let them automatically be assigned to the user level of membership / access?
i.e if we had eventone, eventtwo, eventthree etc. as part of their META, can Membership pro take this info and add the user to a particular subscription?

what i have had to do in past is import users in batches, then tick the usernames individually and then assign a subscription to them - with 20k this would be a very lengthy process

if you can let me know that would be great