Documents where she is the one deciding: signed carrier contracts, approved purchase orders above a threshold, hiring and discipline records, and board or director minutes recording delegated authority to her.
Authority shows up in signatures
Hypothetical example: a Grand Bay-Westfield company sends a petition supported by a business card, an organization chart and a letter from the owner describing his manager as indispensable. None of that shows authority; it shows an opinion about her. What shows authority is a set of documents in which she exercises it.
Pull the carrier agreements she signed, the supply contracts negotiated under her name, purchase approvals above the level requiring an owner's signature, the letter of appointment that gave her the role and stated its powers, and any record of her hiring or dismissing staff. Add the internal policies she wrote. Together these establish that the description in the letter reflects how the company actually runs, which is the point an officer is testing when a small company claims a managerial transfer.