[Exim] rewrite rules

Morning all.

Just a quck question.

Is it possible to have the rewrite rules in a file, rather than in the
cinfig file?
I am using exim 4.10

i need to rewrite the the recipient address before sending to the
manual_route router.

eg.
@booksite.co.za                 %1@???
@dispatch.co.za                 %1@???

Regards,

Tom Kinghorn