BOERUM HILL - Some Brooklyn companies are trying to hammer out health benefits for same-sex couples that are headed for marriage. Business owners say they are deciding whether an employee in a same-sex relationship has to be married to have their health benefits extended to a dependent. Dean Mohs, vice president of insurance services at the Brooklyn Chamber of Commerce, says the new marriage law may simplify the entire process. "With domestic-partner coverage, it gets a lot more complicated," Mohs said. "You have to prove you live together. You're financially interdependent. When you're married, those things are a given."