One of the most valuable assets of the Broad Cove Church, which is fighting to keep ownership of its property in Cushing, is a painting done nearly 60 years ago by famed artist Andrew Wyeth. That painting, a watercolor, is now part of the legal battle between the 170-year-old independent church and an international religious order, the New England Annual Conference of United Methodist Church Inc. But despite the Wyeth name on the piece, Broad Co…