The fourth largest Realtors' association in the United States appointed two presidents Tuesday. The Mainstreet Organization of Realtors named Jack Persin, president of Ryan Hill Realty, and Tom Krettler, broker associate of RE/MAX Unlimited Northwest, co-presidents. MORe now represents about 16,000 members, after the group joined forces with the Realtor Association of NorthWest Chicagoland earlier this year. The combined agencies serve 185 communities in Cook County, DuPage County and Lake County, Ill. The merger is set to close Oct. 1, bringing real estate agents who serve the west, south and northwest suburbs of Chicago under one umbrella. Write to Kerri Panchuk.