Created by is an important audit field and minimally allows the broader organization to know who to go to for questions...E.g. Think PM getting Invoice questions from customers and then needs to speak with whomever created the invoice to review.

Additionally, this impacts many 3rd party integration tools such as Breadwinner that aim to surface Xero data into other systems. The better enabled integration partners are, the more successful Xero will be in growing with customers and entering larger companies.

Enhancement / Use Case:
Enable API to be able to include the name of the person creating an invoice via API (this can be text or reference, e.g. User.XeroUserId) to be set as the Invoice Created By field. Should be optional value, else default to integration user.
It would also be useful to have a property for Options for matching user based on value sent (FirstandLastName, Email, XeroUserId)
Included Created By info in retrieve API so that external systems can provide this info.
Similarly include some options like CreatedBy.Name, CreatedBy.UserId, CreatedBy.EmailAddress that could be selected in field mapping per customers use case would be extremely valuable.