Auto-Link newly imported records to appropriate Partners

Greetings Airtable Community. I am working on a CRM for our referral business. I would like to have an automation that links the new months commissions with the appropriate Partner without having to go through and manually link the name. I start with a new Automation, the trigger is a new record is created on import. What scripting can I start with to query the table, match the MID, and then enter the partner if the MID matches all within the same table. Hopefully the screenshot helps explain.

Watching as I have a very similar problem that I’d like to solve!