[Exim] expansion in router definition

Hello List,

I have the following router definition:

list_aliases:
debug_print = "R: list_aliases for $local_part@$domain"
driver = redirect
file = /tmp/test.list
headers_remove = Received:To
headers_add = To: Stefan Kargl <stefan.kargl@???>
local_parts = test1
domains = example.com

file test.list contains:

"Stefan Kargl" <stefan.kargl@???>
"Sepp Mayer" <sepp.mayer@???>

I now want to replace the "headers_add = To: Stefan Kargl
<stefan.kargl@???>" by a statement that expands to the the
address of each single recipient.

Hence it should add

To: "Stefan Kargl" <stefan.kargl@???> to the first mail
To: "Sepp Mayer" <sepp.mayer@???> to the second mail
and so on

If there is a better way to achieve these results, please tell me.

--
regards
Stefan Kargl