Homesellers have filed another lawsuit against real estate brokerage giants Realogy, RE/MAX, Keller Williams and HomeServices of America challenging the industry practice of having sellers pay buyer brokers. But this suit also adds a new defendant: multiple listing service MLS Property Information Network. While two suits filed last year — known as Moehrl and Sitzer after two lead plaintiffs — sued the above-named brokerage companies, they also sued the National Association of Realtors. The latest suit, filed on Dec. 17 by homesellers Gary Bauman, Mary Jane Bauman and Jennifer Nosalek in a federal court in Massachusetts, does not name NAR as a defendant and instead has named Shrewsbury, Massachusetts-based MLS PIN.