from Biographical Dictionary of Actors, Actresses, Musicians, Dancers volume 4, by Philip Highfill and others.
Caroline (born 20 July 1797) and Teresa (born in January 1799) were apprenticed to another school mistress, a madame Bernard who kept “the school in the New Road near Lisson Grenn” and who on 6 February 1814, was said to have “left her school and deserted her apprentices.”

Had 13 children. (from Grove’s Dictionary of Music and Musicians: Ed. by J.A. Fuller Maitland)

In the 1818 Pallot’s marriage index is Caroline Melissa Danby and Hy. Geo. Nixon, St. Marylebone

Parish records St. Marylebone
October 17, 1818
Henry George Nixon, bachelor
Caroline Melissa Danby, Spinster
In the presence of Charles Danby [probably cousin], Marcella Danby [sister], Teresa Danby [sister]

In the 1841 census civil parish of St. Pancras, Ossulstone hundred (Holborn Division), Middlesex, Registration District St Pancras, sub district Grays Inn Lane.
Henry Nixon age 45, Middlesex, musician.
Catherine [mistake] Nixon age 44, born in Middlesex.
Frances Nixon, female, age 20, born in Middlesex.
Jane [should be James] Nixon age 13, born Middlesex.
Henrietta Nixon age 11, born Middlesex.
Valentine Nixon, male age 5, born in Middlesex.
Maria? Nixon, female age 3, not born in England.
Sophia Nixon age 2, not born in England.

In the 1851 census civil parish of Lambeth, ecclesiastical parish of St Mary, Surrey, Lambeth registration district sub district Lambeth first church living at No. 8 Union Place.
Caroline Nixon, Head of family, widow, age 43 [the date although clear must be a mistake as John Danby could not be her father, this doesn’t match the 1841 census and she would be far too young to have child born in 1819], born at St Giles Middlesex, school mistress.
Daughter Caroline M. Nixon age 23, born Lambeth Surrey, Professor of Music.
Daughter Henrietta G? Nixon age 21, born Holloway Middlesex, Teacher of Dancing.
Son Valentine Nixon age 14, born Holloway, Middlesex, Clerk ?? Office.
Daughter Sophia S? Nixon age 12 born Glasgow.
Son Henry C. Nixon age 8 Hemingdon? London.
Servant Ellen Pursell age 13? born Ireland.

In the April to June 1857 death index there is a Caroline Melisson [as spelled] Nixon, Pancras district volume 1b page 16.

From www.deceasedonline.com
Caroline Melissa Nixon buried July 2, 1857 recorded at St. Pancras Cemetery (Camden)

National Probate Calendar
July 29 1863. Letters of Administration of the Personal estate and effects of Caroline Melissa Nixon late of Stanhope-street Hampstead-road in the County of Middlesex Widow deceased who died 28 June 1857 at Stanhope-street aforesaid were granted at the Principal registry to Caroline Frances Lamb (Wife of Edward Buckton Lamb) of 3 Hinde-street Manchester Square in the said County the Daughter of the said Deceased she having been first sworn. Effects under 200 pounds.

Musical Scotland, past and Present:Being a dictionary of Scottish Musicians
born Winchester, 20th February , 1796.; died London 1849. Organist and church composer. He was organist at St. Andrew’s Roman Catholic Church, Glasgow (1833-39), his eldest daughter being organist at St Jude’s Episcopal Church. In 1839 he returned to London, and was organist at St George’s Roman Catholic Cathedra; till his death. . . . H. G. Nixon composed five masses, a Te Deum, a cantana - composed for Mad. Malibran - and many Latin Services for the Romish Church.

He was the organist at St George’s Chapel, London Road from 1817 to 1820; next of Warwick Street Chapel, 1820-36 ; St Andrew’s Catholic Chapel, Glasgow, and at St George’s Cathedral, Southwark, in 1839, until his death in in 1849.
Died of Cholera

In the July to September 1849 death index Henry George Nixon, Lambeth, volume 4, page 399.

London Burials St. Mary’s Lambeth
Henry George Nixon, 22 Canterbury Place, buried September 14, 1849, age 54.