What is the fine-grained topic of the following text: The NPSL, a fourth-tier U.S. Soccer organization, features more than 60 teams, and FC Frederick will compete in the six-team Mid-Atlantic Conference of the NPSL’s Northeast Region along with ASA Charge, Chesterfield United FC, Fredericksburg FC, Legacy 76 and Virginia Beach City FC. Only return the topic.
FC Frederick joining the Mid-Atlantic Conference of the NPSL's Northeast Region