NetSuite and Custom Fields Mappings

I’m trying to update some custom fields via the NetSuite ASync Upsert Snap. I can successfully update data when its not a custom field but instead a standard one. When I want to update the custom fields the only option to do that is on the NetSuite ASync Upsert snap itself (past the snap that I map the values to the standard $record[*] fields. I find though that since I map the custom fields to a custom variable the NetSuite Async Upsert doesn’t like the format of the XML being passed into it. How can I resolve it? Below the company_id is the custom entity field on Customer: