That was about the only blemish on Reynolds' copybook.
Sio scored in the corner in the 12th minute, but Reynolds and Sutton turned the game around with their well-executed option taking.
Centre Dylan Walker crossed in the 17th minute after a Reynolds stab kick deflected off Eels five-eighth Joseph Paulo and wrongfooted Parramatta fullback Jake Mullaney.
After 29 minutes, Sutton offloaded to Justin Hunt, whose well placed kick was touched down for a try by wing Dylan Farrell.
It took just three minutes of the second half for Souths to extend their 12-4 halftime lead to a 14-point advantage. Another Reynolds kick set up a try to Hunt.
Sio's intercept try provided a rare moment of joy for Parramatta, but Reynolds brushed off some flimsy defence for the Rabbitohs' fourth try.
Busy hooker Issac Luke drew defenders to set up a clear passage for Sutton to score South Sydney's fifth and final try in the 63rd minute.
- AAP