[Exim] forwarding

hi!

I use exim with mysql lookups.
I let my users to specify a forward address, and i store it in a
database table.
If forward address is set for the user, i use this director:

virtual_aliases:
driver = aliasfile
domains = ${lookup mysql {select domain from domains where
domain='${domain}' and dtype='maildomain'}{$value}}
search_type = mysql
query = "select u.forward from users as u,domains as d where u.domain_id
= d.domain_id and d.domain = '${domain}' and u.user = '${local_part}' and
u.type ='alias'"

and this worx fine, if fw addr. is set, this directs the message to it.
but, i don`t know how to do this forwarding, if i want to leave a copy for
the user on my server too in /var/mail/${domain}/${local_part}, or if i
had two forward addresses....
could anyone help me in that?

thx,

{pai}