RapidStart - Move field data into another field (same table) on import

I'm moving data using rapidstart from an very old database.

In several tables we created 50xxx range fields that didn't exist in our version however they do exist in the NAV 17 version. For example the Salesperson/Purcahsor table contains email which we created 50000 - Email.

Is there a way to map fields in the rapidstart environment? For example on import field data in 50000 -> field 5052.

I've probably sent more time trying to find the answer whereas i could have just wrote code to do so, but I'm trying to avoid writing code to handle each of these.

Thanks