Disbursements at domestic ports other than the principal office of the agent for expenses as referred to in section 5 shall be made by one of the three following methods:

(a) After proper certification by the branch house or subagent, invoices shall be forwarded to the agent for payment, or

(b) The branch house or subagent shall pay invoices and thereafter apply to the agent for reimbursement, supporting its voucher with invoices bearing evidence of payment covering individual disbursement, or

(c) The agent may advance from time to time from the joint bank account the funds necessary to meet the requirements of such branch houses or subagents in connection with the activities, maintenance and business of the vessels assigned under the agency agreement. In such cases the branch house or subagent shall pay invoices from such advances and make proper accounting to the agent for each advance supported by invoices bearing evidence of payment and accompanied by remittance covering any unexpended balance of the advance, promptly after the departure of each vessel for which such advance was made.