I have two custom fields on the Opportunity object, one is picklist field and the other is lookup field that's related to a custom object. The lookup field is a new field that has been added after the fact. If the picklist is a certain value: "A", "B", "C" or "D", I want the lookup field to return the corresponding record of the custom object using the recordID.
So if picklist = "A", then lookup field will return the custom object record "A", and so on.
Is this possible using Flow Builder? I'm new to this so if you need further clarification, or I've gotten it completely wrong, you won't hurt my feelings.
And can this be done on Opportunity records that already exist with the picklist values already selected?