[SalesForce] How to i add a formula field into a Opportunity Product Multi-Line Layout

You should look at the Snazzy Product Entry Screen from Michael Farrington. We use this internally and since it's an unmanaged package, you can customize it to your needs. I would think your "quantity" requirement would be easy to add to this.

This essentially replaces the add product page and the multiline edit page. It sounds like it might be exactly what you are looking for.

Assuming that you can use a formula to concatenate the product code and quote code you can do this without any custom code.

• Add a custom text field for users to enter the quote portion of the code and add it to your multi-line layout.
• Create a formula to concatenate the product code and the quote code the users have entered: Product2.ProductCode + quote_code__c

I would recommend using the standard ProductCode field to store the "production code" as you cannot add custom product fields to the quote item multi-line layout.

If you need the full concatenated code to remain the same when the product code changes you can just change this to a workflow rule that runs on create.