[Exim] Globbing in searches

I might be missing something, including basic understanding :-) but here goes
anyway...

1. Scenario: /etc/mail/domain_aliases contains lsearch files foo.com &
bar.net -- a subset of local_domains. I would like to have my first director
look there first (e.g. file = /etc/mail/domain_aliases/$domain) and then if
that fails (e.g. the file doesn't exist) try the usual system_aliases
director which uses /etc/aliases. (I could do this with condition =
<test-for-existence> .../$domain. Is there a way besides ${perl} to do that?)

The thing I'm trying to do is have a few domains that have special cases,
e.g. all emails are forwarded. I could achieve that if, for example,
include_domains allowed just local_part to match all domains and then have a
few *@odd.domain: external@???

2. In a similar vein, is it possible to do something like local_domains =
/etc/bind/master/forward/* to have exim treat all the domains my nameserver
is serving as local domains (assuming of course my zonefile names match those
domain names). What I'm trying to avoid is having to maintain a separate file
that is essentially the same information elsewhere (e.g. output of ls).

Thanks,
Paul