In set service dhcp-server I can specify global-parameters free-form according to the format of dhcpd.conf. Further, I can specify parameters at the shared-network-name or subnet level. This is important for adding custom DHCP options.
In DHCPv6 I do not have this ability through set service dhcpv6-server.
This feature request is to add the same capability for free-form parameters/options entry as is available in the DHCP server.