Sidney has a large and often times complicated family tree. There are four families associated with her: Riley, which is her father's family; Lightfoot, which is her mother's family; Lee, which is her adoptive family; And, she also has unknown Deltan relatives on Delta IV.
- Alsandair Ryan Riley: Terran (Irish) Sidney's Grandfather.
- Shannon Rylyn Riley: Terran (Irish) Sidney's Grandmother.
- Liam Alsandair Riley: Terran (Irish) Ryan's Brother and Sidney's Uncle. He is married to Anya. They have seven children (Sidney's Cousins); Tynan, Rowan, Mairead, Megan, Cara, Patrick, and Dugan.
- Ryan Aidan Riley: (November 20, 2329-September 24, 2355) Terran (Irish), Sidney's Father. He was an Engineer in Starfleet. When he disappeared in 2361 he was a Lieutenant.
- Dairine Alyce Riley: (August 5, 2332- ) Terran (Irish) Ryan's sister and Sidney's Aunt. She is married to Brian McKeegan. They have four children (Sidney's Cousins); Tara, Rylyn, Alsandair, and Brady.
- Tynan Riley: (2345- ) Terran, Sidney's Cousin. Has two children; Sabine (2363) and Rowan (2364).
- Rowan Riley-Stevens: (2346- ) Terran, Sidney's Cousin. Has two children; Douglas (2362) and Lucy (2365).
- Lucy Stevens: (2365- ) Terran, Sidney's Second Cousin. Has one son, Liam (2382)
- Patrick Morgan Riley: (2347- ) Terran, Sidney's Cousin. No Children.
- Tara McKeegan-Peters: (2349- ) Terran, Sidney's Cousin. Married to Greg Peters and has two children (Sidney's Second Cousins); Molly and Arthur.
- Rylyn McKeegan: (2350- ) Terran, Sidney's Cousin. Has one son (Sidney's Second Cousin), Alan (2371).
- Alsandair McKeegan: (2352- ) Terran, Sidney's Cousin.
- Brady McKeegan: (2355- ) Terran, Sidney's Cousin. Has one daughter, Lorielee (2384)
- Shannon Alyce Riley: (July 24, 2350- ) Sidney's Identical Twin Sister.
- Benjamin Lightfoot:(May 6,2307- ) Terran (Native American) Sidney's Grandfather. He has developed eccentic behaviors in his old age. Now believes his deceased wife and daughter were not human, but refuses to talk about it to anyone but Maharet. Benjamin cares greatly about his grand-daughters. Sidney was always close to him; she calls him "Bear".
- Imara Lightfoot: (July 10, 2315-April 4, 2334) 1/2 Terran (Native American), 1/2 Deltan Sidney's Grandmother. Raven's mother and Ben's wife. Nothing is known about her beyond this fact. Benjamin refuses to talk about her.
- Raven Lightfoot: (July 20, 2332- December 15, 2358) 3/4 Terran (Native American), 1/4 Deltan Sidney's Birth Mother. Raven was strikingly beautiful with deep red skin and long flowing black hair. She is the mother of Sidney, Shannon and Maharet. Not much is known about her beyond these facts, partially because Benjamin refuses to talk about her. He has however stated she was not fully human.
- Maharet Lightfoot: (June 6, 2354- ) 7/8 Terran (Native American), 1/8 Deltan Sidney's Half Sister. Maharet is a Doctor on Earth. She one day hopes to attend the Academy and join Starfleet. She is very close to Sidney. For most of her life Sidney believed Maharet was her cousin. When she was 26 she learned that Maharet was her half-sister through their birth mother Raven. Maharet has a very outgoing personality. She loves to talk and is not afraid to say what she thinks.
- Moira Marie Lightfoot: (March 24, 2380- ) 15/16 Terran (Native American), 1/16 Deltan Sidney's Niece. Daughter of Maharet Lightfoot, Sidney's half sister. She is a Fourth Grade student at a private school in New Orleans.
- Cheyenne Lee (Riley): Sidney's Adoptive Mother. Cheyenne is Raven Lightfoot's cousin. Cheyenne was married to Ryan Riley until they divorced in 2355. Cheyenne was very fond of Ryan's daughter Shannon. When Ryan and Shannon divorced it was decided Shannon would stay with her. When Ryan and Shannon disappeared in late 2355, Sidney went to live with Cheyenne and her husband Tarvik on Vulcan.
- Tarvik: Vulcan, Married to Cheyenne Lee (Sidney's Step-Father), Instructor at the Vulcan Science Academy. He believes Sidney should have studied at the Vulcan Science Academy instead of joining Starfleet.
- Tavik: Vulcan, Sidney's Step-Brother, Vulcan Astronomer. Sidney was very close to Tavik when she lived on Vulcan. They grew up together. He was the one who encouraged her to follow her dream of joining Starfleet.
- Soria: Vulcan, Sidney's Step-Sister, Student at Vulcan Science Academy. Very logical, Soria did not approve of Sidney's behavior much of the time. Sidney did not spend much time with her step-sister. They are not close and do not talk much.
The Riley family home is situated on the West Bank of the Mississippi River in New Orleans, Louisiana. The home is a plantation style home built in the year 1862 (age of home approximately 525 years). The two story house sits on 5 acres of land.
The exterior of the main house is white brick, with four large columns in the front and back. Other features include a wrap around porch with wrought iron railings and wrap around balcony also featuring the same wrought iron railing as the lower porch.
The main house has five bedrooms, three bathrooms, a dining room, office/library, music room and a sunroom. The kitchen is a separate building on the North side of the home with a small passageway leading to the dining area.
The interior of the home also features 6 fireplaces and a large basement. In the twentieth century, part of the basement was converted to a wine cellar.
On the grounds, there is a large old willow tree situated near the levee. There is a grove a trees near the North side of the home, large old trees with moss hanging from them. There is a long dirt driveway which leads through the grove and up to the main house. Also on the property are a two story carriage house, a large old barn that is as old as the house, and a medium sized barn which houses five horses.