Bruce, thanks for the reply.
I think if I understand you correctly, the "You have been added" message in the link that I posted is separate from the "Welcome" notice. Is this correct? So when I transfer my Yahoo Group, members will receive both the Welcome notice that I've customized, and the "You have been added" message that I cannot customize?
It would be great if the wiki page could make that more clear, if that's the case.