[exim] filter using multiple files

Hi,
I would like to filter and dispatch my incoming mails to my Maildir
folders and subfolders, in the criteria of the List-Id or X-Mailing-List
header (on some MLs, I'll have to use the "To:" one...)

I know how to do it, but in a monolithic ".forward" file.
It would be great if I could use one file per filter (per ML then).

What would be the solution?
I have no access to the system, just my $HOME.