I've done quite a bit the last few years while my boys skied/boarded. You can't expect to force quick, pristine parallel turns out of this set-up. I've found deliberately stepping into turns on one ski, letting the ski becoming the uphill ski float along for the ride, and then stepping on that ski for the next turn, works better. Before I skied Downhill/Alpine parallel well, I was taught what was called a "Modified Stem Christie". This was the transitional technique after snow-plow. My mountaineering boot/AT set-up technique is a cleaner, more "parallel" modified stem christie, I guess.
Conditions have to be good, also. Ice and steep runs should be avoided.
I hope that makes sense.