Manage Customer Debit Notes

Hi,

Hope someone can help me, I'm trying to manage a Customer Debit note in the system (in my country a debit note must be a different type of transaction and a different type of document), the concept behind it is the opossite of a credit note allowing to debit the customer´s account, increasing the accounts receivable amount.

What I've done so far is a copy of the credit notes applications and scripts changing those files to debit, creating a new transaction type 14 (ST_CUSTDEBIT), but when I want to create the journal entries I must modify the sales_credit_db.inc (this is the file I suppose create the GL transactions), I copy the file and renamed as sales_debit_db.inc, but I still get the same result as the credit note.

My questions are how the credit note creates the journal entries? and Which functions are used in the creation of GL lines when process credit notes?

Thanks for your help