David Einhorn, who has been selected to join the Mets ownership group as a minority partner, has a path to majority ownership, according to a source. Einhorn has agreed in principal to purchase roughly 33 percent of the team for $200 million, which will infuse cash and keep the organization solvent in the immediate future. In three years, according to the source, Einhorn has an option to up his stake to 60 percent, although principal owner Fred Wilpon and his family have an opportunity to block Einhorn from gaining that majority stake.