You can try using metabisulfate and sorbate in that way, but I would be very cautious and start with a small sample size (like 1 bottle) as a test. The addition of these two chemicals isn't intended to stop an active fermentation. They are intended to prevent fermentation from restarting when additional sugars are introduced. So you normally want to add the sorbate first, and backsweeten afterward. Obviously this will prevent the carbonation you're trying to get.
My first recommendation for sweetened and carbonated cider would be to get a keg. You can then make your cider how you want it, force carbonate, and bottle. If you don't want to go that route, I would try pasteurization by raising the temperature (never tried that myself). As mentioned, you can try an addition of adding metabisulfate and sorbate, then recapping the bottles. But I would be skeptical of the reliability and consistency of this.