How to made openwrt add client route automatic under ipv6 relay mode

after set up ipv6 relay mode, openwrt's clients can access outer public ipv6 successful, but clients cannot be visited from outer public ipv6 host. after add below route rule, openwrt clients can be visited from outer public ipv6 now, is there a way to made such a route rule added automatic and correct by openwrt itself, no matter what's client's ipv6 it is?

route add xxx:xxx:xxx:xxx:d4ae:48ae:24ee:c075 dev br-lan