Change an IP address without a reboot

[Andrew Falanga]

Yesterday I asked a couple of questions about networking (assuming that it
actually went to the list, I never saw my message in my inbox which makes me
wonder if it was ever posted to the list).  I've worked out the issue with
IPv6, now the only remaining question is how does one actually change the IP
address that FreeBSD is using in such a way that the first address is
dicarded.  I'm not in front of the machine, but I have the network currently
not configured.  I'll be changing things on the fly often given what I'm
working on.

When it boots, I log in and configure an IPv6 address like this:

ifconfig sis0 inet6 fec0:1:1:1::3/64

Which works just great.  It so happens in this little isolated network I'm
building, this address was taken, so then I did the exact same command as
above only I gave it the address of fec0:1:1:1::2/64.  The part that I want
to know how to eliminate is, after issuing the second command, I listed the
interface configuration using ifconfig and both the addresses were present.
How can I eliminate the first address?  I've looked over the ifconfig manual
page several times, each time reading it just a little bit more carefully,
but I haven't found anything that answers this question.  Would some kind
person please help me out and show me what it is that's eluding me from
making this happen?

Thanks,
Andy