[Dovecot] Personal Sieve Resieving Default Sieve?

Hello all. In my dovecot install we have a default.sieve script which filters incoming mail based on the subdomain of our main domain. All it does is if the mail comes from A.domain.com move in to folder A in inbox, and if it comes from B.domain.com, move to folder B also in inbox.

In my personal sieve script, I'd like to grab a particular email each day that the default.sieve saw coming from A.domain.com and moved it to folder A, and either copy or move it to another folder, C. My google-fu was weak while looking for second sieve passes undoing the first, so I thought it best to ask here.

Thanks for your time.