In the case of optional group policies, notwithstanding the same article L. 113-9, omission or misrepresentation on the part of a member who has not acted in bad faith shall not render the insurance null and void. If it is established before the risk materialises, the insurance undertaking has the right to maintain the contract, subject to an increase in the premium accepted by the member; in the absence of the member’s agreement, membership of the contract terminates ten days after notification is sent to the member by registered letter; the insurance undertaking refunds the portion of the premium paid for the time during which the insurance is no longer in force. In the event that the declaration is only made after a claim has been made, the indemnity is reduced in proportion to the rate of premiums paid compared to the rate of premiums that would have been due if the risks had been fully and accurately declared.