Interesting Rewriting Desires

In our rather deranged mail setup, we need to rewrite the "from:"
addresses of messages whose "to:" have addresses match
"*-request@???" rewritten using an existing
from-address rewriter. So far as I can tell, there is no way to do this
without using the rewrite-all-headers option. (Because matching by
the "to:" field seems to imply that I want to rewrite the to "to:" field,
instead of the "from:" field.) Because that would add unneeded ugliness
to our config file (and complication to our rewriter), is there a better
way to do this?

Thanks.

-Chris