Bava Batra 167 - Who Can Authorize Document Preparation and Who Pays the Fee
Generally, for documents to be legally valid, they must be written with the knowledge and consent of the one to whose detriment they are. For example, a loan document can be written only with the authorization of the borrower. An exception is a Get, a bill of divorce.
A scribe may write a Get for a man even if his wife is not with him. In the eleventh century Rabbeinu Gershom instituted a ban against divorcing one's wife against her will. He may also write a receipt for a woman, stating that she received her Ketubah, even if her husband is not with her, and the husband pays the fee.
A loan document may be written for the borrower even if the lender is not with him, but not for the lender, unless the borrower is with him, and the borrower pays the fee.
Art: Rembrandt - Titus at his desk