need some clarification:

if i ssh to the server & i restart the sshd process, did my connection gone?
one more thing, there are a few sshd processes in aix, how do i restart it all to read new config? using HUP?

thanks in advance!

stopsrc -g ssh and then startsrc -g ssh

New connections will not be possible while stopped. Existing connections should be fine.

You can also do a kill -1 on the process. You'll find the pid listed in a file in a directory like /etc/ssh.