If you configure your OOTP saved game to be an online league, you could do this. See
this section of the manual for more information.
However, that may not mean that you need to run your league as an online league. It may be possible to configure it as an online league but never set up any human managers. But then the AI is going to handle all of the rosters, transactions, and other business unless you plan on doing all of that work on behalf of your GMs. But that would be an absolute nightmare.
Unless you just want to allow your GMs to draft players and leave everything else to the AI, I would strongly encourage you to get every member of your league to buy OOTP Baseball. It's easy to configure your league. And your GMs can easily download the latest league file from within the game and submit their lineups, changes, contract offers, or other business for each sim period.
Otherwise, in the immortal words of Walter Sobchak, "you're entering a world of pain."