FreeBSD 10 Multiple IPs in a jail

[dweimer]

I know that we can now do multiple IPs in a jail, and I have a 
configuration that works for it.

jail.conf:
testjail {
         jid = 100;
         host.hostname = testjail.local;
         ip4.addr = 'em0|10.20.190.190/24';
         ip4.addr += 'em0|10.20.190.191/24';
         path = /jails/devel/ROOT;
         allow.mount.devfs;
         mount.devfs;
         allow.sysvipc;
         exec.start = "/bin/sh /etc/rc";
         exec.stop = "/bin/sh /etc/rc.shutdown";
         exec.prestart = "/jails/devel/prestart.sh";
         exec.poststop = "/jails/devel/poststop.sh";
         exec.consolelog = "/jails/devel/console.log";
}

This works great, my question is now that I have this figured out and I 
am done testing it, how can I apply it to a running jail without 
rebooting the jail?

I tried using:
   jail -n testjail -m 'ip4.addr='em0|10.20.190.191/24'
   This replaces the IP on the jail.

Then I tried using:
   jail -n testjail -m 'ip4.addr+='em0|10.20.190.191/24'
   I get an error "unknown parameter ip4.addr+"

Am I stuck waiting until after hours to add the secondary IP when I can 
reboot the production jail?  Or is there another way I haven't figured 
out yet to add the secondary IP to the running jail?

-- 
Thanks,
    Dean E. Weimer
    http://www.dweimer.net/