If you wanted to change MCN while being partnered with Freedom than that's fine. All that you will need to do is request to unlink with Freedom, which you can do via the feature section on Youtube, and after the 30 days are up then you would be free to join the other MCN. All that I would say is look into the MCN as I know that freedom does operate a few MCN as well, so you may just be able to transfer straight over if it is one of Freedom's MCNs