If there is no written authorization from the parties concerned, they cannot sign on their behalf. You should bear legal responsibility for issuing invoices on your behalf. If the agent is legally authorized by the parties or the parties ratify the contract afterwards, the legal consequences of the contract's entry into force shall be borne by the client; If the signing agent has no authorization or exceeds the scope of authorization, the legal consequences arising from the signing agent shall be borne by the signing agent.