I certainly understand that in most areas of the function of a 401(k) plan, sponsors have the potential to create a myriad of issues. I wasn't asking whether it's a good or bad idea—just what rule exists.
I appreciate you weighing in. A former colleague said a sponsor couldn't attempt to use a prefunded account to see any gains while another colleague told me the fund used is at the sponsor's discretion and I couldn't find anything about the matter online.