Turned out to be easy, and you can do it two different ways:
1) Turn on the alias file options in the sendmail.cf, e.g., pointing to /etc/mail/aliases. The add aliases to that file (including using the "include" command for files). NetInfo and these aliases seem to coexist peacefully.
2) use the include command as the alias in NetInfo, the alias being ":include:<absolute-file-name>" .
Works like a charm.
Now, when can we get remote access to NetInfo maintenance...?