Is it possible to merge dbx files into one identity?

I have transferred my emails from MN to FL for 4 years now, but I keep
forgetting to record my identity, and have used several different ones. As a
result, I have at least 4 dbx files holding emails, some of which I would
like to keep and consolidate with my present identity. In this way, I will
delete the other identities to get rid of this confusion.