Marble Falls City Council may approve an ambitious retail development south of the city during its May meeting.Flatrock Development Group Part- ners LLC plans to build a shopping cen - ter in the area Flatrock Creek along U.S. 281. The site, just off highway frontage in southern Marble Falls, is between a 7-11 (at the corner of RM2147 East) and the Charley Taylor Rodeo Arena.During its March…