I knew all that, I wanted a way to turn off the ipv6 addresses without assigning any v4 addresses by dhcp or static. if you read up on bridging in openBSD [section 6.9 in the link you posted] you'll see that having ip addresses on the interfaces in the bridge takes them out of promiscuous mode. which stops them from doing anything with traffic not bound for their ip address. currently I am using this quick fix...
!ifconfig ifname inet6 inet6address delete
in both of the hostname.if files because I noticed that every time they came up the ipv6 address was the same. this works but it seems like a bandaid solution, basically it turns on the interface which comes up with a v6 address and then manually deletes the v6 address on the command line. can anyone point me to the correct way to fix this?