Split function helpful to split selected order lines and create new invoice/bill/credit note/debit note and remove selected lines from the existing invoice/bill/credit note/debit note. In the split function, you have 2 options, new & existing. Extract function helpful to extract order lines without removing from the existing invoice/bill/credit note/debit note. We have added a checkbox in product lines so it will help you to decide which item you want to split/extract. Whatever ticked products will go in the wizard for split/extract who is in the "Draft" state. If you don't tick then it will add all items in the wizard.