Faith Tolliver is Jacqueline Sloane's biological daughter, whom she gave up for adoption shortly after birth.
NCIS Season 16
Faith was first shown in episode 10 What Child Is This? when Sloane was looking through a photo album. Faith actually appeared in the season 16 episode Perennial, where she was a witness in an active mass shooting.
NCIS Season 17
Faith appeared in the 8th episode, Musical Chairs, and asked Jack to fill out some medical forms with family history information. Faith was mentioned in the 15th episode, Lonely Hearts, when she sent Jack a Valentine gift and a card. In the 18th episode, Schooled, Faith went to visit Sloane again, and asked about her biological father and revealed that she is engaged and currently undergoing fertility treatments.