Two Omaha-based commercial real estate development and management firms are joining forces, the Omaha World-Herald reported. World Group Commercial Real Estate will be formed through the merger of Seldin Co., an 88-year-old family-owned firm, and Coldwell Banker World Group. The company, which will control more than 3 million square feet of retail, office and industrial space in the Omaha metropolitan area, will employ 40 people. Formal talks regarding the proposed merger began in May 2010. Seldin Co., which owns and manages 8,000 apartment complexes in the Midwest, will continue to operate as a separate entity.