Hi TM

You can split your 5.1file into 6 mono tracks within PP if you want to. Just highlight the file, then Clip>Audio Options>Breakout to Mono.

You obviously need to set up your timeline with as many mono tracks as needed, and decide if you want a master surround or stereo mix. Then you treat each mono track seperately. So you'll need to mix them individually to get the balance you want.