RA for a different router

[Bit Gossip]

Experts,
do you know if it is possible to use RA for the router to advertise not
itself but some other address as the default router for the prefix?

I had a look also at DHCPv6 for the same purpose but no option, at list
with IOS for doing that.... Is it possible with DHCPv6?

3660(config-dhcp)#?
IPv6 DHCP configuration commands:
  default            Set a command to its defaults
  dns-server         DNS servers
  domain-name        Domain name to complete unqualified host names
  exit               Exit from DHCPv6 configuration mode
  import             Import options
  information        Information refresh option
  nis                NIS server options
  nisp               NISP server options
  no                 Negate a command or set its defaults
  prefix-delegation  IPv6 prefix delegation
  sip                SIP server options
  sntp               SNTP server options



Any other way?

Thanks,
bit