Only by matching the client's DUID with a static IPv6 at the router's side, or if the client provisions the option to change from DHCP and set a static IPv6 that matches the network subnet.
Seems you asked that question already in another thread.
DUID, as opposed to MAC, is not necessarily hardcoded (MAC often being printed on sticker), but often soft generated during a device setup (reset). Hardcoded DUID are specified as per DUID-EN.
Some vendors may fail on proper DHCPv6 a/o DUID implementation.