Centred AND Panned/Effected DIY acapella rips

HELP!!!

I’m trying to DIY acappela a track with limited success..

I can rip the centred (stronger) vocal with ease but there’s a panned flanged/unison’d vocal which is hard to get other than probably making the whole track mono n mixing it back into the stereo track at a higher volume and then try rip the ‘other’ vocal from there (together with a tonne of other crap that might show up.)

Ive not tried it yet as I wanna know if anyone has any hints, tips or successes trying to rip similar acapellas.

Other than that I’m just gonna appeal to the better nature of the group in question n ask thru various channels for the full acapella of the track to work with and explain I’m not doing it for commercial gain.