Last week brought word that Boston Medical Center and Tufts Medical Center were moving ahead with merger talks and expect to have a deal by the end of this year. The parties announced they were exploring a merger last December. That news came two days after Massachusetts Attorney General Maura Healey and House Majority Leader Ron Mariano announced legislation that would give more power to the state’s Health Policy Commission in its reviews of hospital mergers and acquisitions. No such headaches exist in New Jersey, where Meridian Health Systems, which operates six hospitals, merged with financially troubled Raritan Bay Health Services Corp., a two-hospital system. Meridian is still in talks to merge with Hackensack University Health Network, announced in October 2014. Then there’s the merger between Wellmont Health System, which operates six hospitals in northeast Tennessee and southwest Virginia, and Mountain States Health Alliance. It’s getting so you can’t tell the players without a program.