Cymphonyque Miller is the leader. The other 2 are not mentioned, but they are backup dancers for her in real life.
The guys have no kids but Stephen Glickman (aka gustavo) has a daughter
James: 6'1 Kendall: 5'11Logan: 5'11Carlos: 5'6
Logan is 5 foot 8
James from big time rush is at the least 6 feet tall because kendall is 5'11