There isn’t enough information here to do a lookup. As I read this, you want to lookup a business name in your Vendors database, and put that name into the Business Name field of your Customers database, but there needs to be some way of recognizing the record containing that name.
When you lookup a number in a phone book, you begin by looking for the name of the person or business in question, and once you have found it, you read the number on that same line in the book.
A lookup in a database works the same way. There has to be something you already know, that the function can look for, so that it will know when it has found the record. That something is called the key value, and the field where you expect to find it, is the key field.
A superlookup( will look for a record that satisfies a true/false formula, and retrieve the value from that record. Without knowing what criteria you want to use to find the record, I don’t think that anyone can help you with this.