[Exim] how to insert manual logging in a redirect router ?

I've created a mysql lookup forwarder (the virtual_forward router)
I works but when I view the main_log it shows
<= sender mailaddress
=> forwarder mailaddress

I would like to insert a log entry where I can se the original TO: mailaddress

like

<= sender mailaddress
== forwarding from orginal mailaddress to
=> forwarder mailaddress

Can this be done ?

I have tried the documentation, FAQ and maillist archives, and if it's in there .. I've missed it.

Cheers,
Flemming

Part of my router config:

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dnslookup:
driver = dnslookup
domains = ! +hosted_domains
transport = remote_smtp
ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
no_more

virtual_forward:
driver = redirect
domains = +virual_domains
data = ${lookup mysql {MYSQL_SELECTFORWARD}}

virtual_domain_users:
driver = accept
domains = +virtual_domains
condition = ${if eq {} {${lookup mysql {MYSQL_SELECTUSER}}} {no}{yes}}
transport = virtual_domain_delivery

virtual_domain_defaultusers:
driver = accept
domains = +virtual_domains
condition = ${if eq {} {${lookup mysql {MYSQL_SELECTDEFAULTUSER}}} {no}{yes}}
transport = virtual_domain_defaultdelivery

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