pfSense

since I can't find very detailed information on how carp works (under the hood i mean) i've read some documentation on vrrp as those protocols have a lot in common. however, it is stated in vrrp draft (http://tools.ietf.org/html/draft-ietf-vrrp-spec-v2-10#section-5.1) that one can have multiple ip's in a vrrp vhid group. And, when I tcpdump i see that currently carp sets number of ip's to 7 and then adds 7 ip's to the vrrp packet. I cannot find any relation between the carp'ed ip and the addresses that are in the packet related to that vhid btw.
So, we would like to have the functionality of pfsense's (freebsd maybe even?) carp implementation extended to support multiple ip's per carp vhid. (vrrp seems to support only up to 20 ip's btw, i guess due to ethernet packetsize limit?)