First Federal Credit Union has plans to open its fifth office, in Marion, around the first quarter 2020.The credit union announced late last week it signed an agreement to become the initial tenant in Genesis Equities’ retail development at the intersection of Seventh Avenue and 26th Street. The new branch will occupy approximately 2,800 square feet of the 11,000-square-foot project the Marion-based developer is building.The First Federal Credit Union opened its doors in 1926 and has two offices in Cedar Rapids, and one office apiece in Hiawatha and Spencer.