[exim] different server same domain

hi all,
i'm really new in exim.

I'd like to configure to forward different account, belonging to the same
domain, to different server.
I mean,
1) when exim gets an email for bill@???, it must be forwarded to
bill@??? (server X)
2) when exim gets an email for rose@???, it must be forwarded to
rose@??? (server Y)

How can i do that?
could some one let me know the correct way?

Thanks a lot in advance

Lore