So our Ohtani solution turned out to not be a solution, because you can't identify specific players that can exist more than once in our league. Either all players exist in duplicate, or none do. There are three possible solutions to the problem, unless someone sees something I'm not thinking of:
1) Ohtani lives on Dinger's roster and is moved by a commish to EZe's roster for every start.
2) Dinger and EZe work out a trade.
3) Dinger or EZe work out a deal with the league to sell their Ohtani for compensation (ex. top X MiLB or waiver pick the next Y years, the ability to pick any X available minor league players and hold them in addition to regular farm limits etc...). Surely there's some compensation that you would value above your Ohtani. Make an offer.