Reply to Software and Hardware mixing? Possible?

Question, not sure if it's possible.

I currently own a DJM-250, which I love (hardware mixers espically filters sound so much nicer than software). I want to expand the decks, and I have been coming up with some midi controller designs in my head that would be purely software driven. here's what i've been believeing for a set up (I use traktor currently, i also have live):

-computer sends tracks a-b to audio card
-audio card sends decks a & b to djm 250
-audio card accepts master out from djm 250 (mixed) to an audio in
-audio card accepts headphones out from djm 250 to an audio in
-computer accepts inputs from midi controller 1 for deck a & b transport controls (usb)
-computer accepts inputs from midi controller 2 for deck c & d transport, and mixing controls (usb)

now here's the question:
-can the audiocard or software combine the master output from djm 250 (tracks a & b) with ONLY the software mixed tracks (c & d) for one master output?
-can the audio card or software combine the djm 250 headphones out (tracks a & b) with ONLY the software mixed tracks (c & d) for one headphones out?

thanks in advance,
-DB