postfix + multiple domains + multiple alias-files ?

Hi!

I'm trying to setup postfix managing smtp-traffic for more than one domain.
Can postfix handle multiple aliases-files like exim can?

Example:

There are five domains and I want to handle the aliases for two of them in a
file and the aliases for the other three domains in another file.

In Exim i can configure one or more aliases-files, each file can contain
information for multiple domains

I considered using virtual maps, but i would have to add each alias at least
three times (for every domain)... is there an easier way to do that?

Thank you,

Stefan