I have a new custom object (let's call it fancyobject) that I want to have use Accounts as parents (i.e. there will be many fancyobjects for each account).
The purpose of this is to upload data from a product on a daily basis. The data upload will include an external unique ID, but not the account name. The external unique Id has been created in the Account object and listed as a unique identifier.
But I can't figure out how to make that unique ID the link in my master-detail relationship with the Accounts. I want the fancyobject to belong to an account. But I need the look-up link (to establish which account is the parent after upload) to be the unique ID field. Is there a way to do this?