[Exim] double delivery

Hello All,

Anybody can help me?
I don't know ho to create delivery for thi situation:
If recipient declared in the alias file (/etc/alias) then deliver this mail
to local folder use "local_delivery" transport otherwise try send this email
to cyrus mail server by "local_delivery_cyrus".
I will very gland for any help and config samples :).

P.S. I use Exim 4.

~ Sergey Merkuriev