OK a quick review of who seem to be Mary's brothers and sister,
BaptismsMary Ann ROBERTSON
05 February 1832
Father: Robert ROBERTSON, Confectioner
Mother: Mary Ann
Residence: Brompton Row
Parish or Poor Law Union: Brompton Holy Trinity
Borough: Kensington and Chelsea
Robert ROBERTSON
29 September 1833
Father: Robert ROBERTSON, Confectioner
Mother: Mary Ann
Residence: Brompton Row
Parish or Poor Law Union: Brompton Holy Trinity
Borough: Kensington and Chelsea
Emma ROBERTSON
01 March 1835
Father: Robert ROBERTSON, Confectioner
Mother: Mary Ann
Residence: Brompton Row
Parish or Poor Law Union: Brompton Holy Trinity
Borough: Kensington and Chelsea
Edward ROBERTSON
Baptism: 23 Oct 1836
Father: Robert ROBERTSON, Confectioner
Mother: Mary Ann
Residence: Brompton Row
Parish or Poor Law Union: Brompton Holy Trinity
Borough: Kensington and Chelsea
Also I found this possible Burial for Robert Snr,
Burial Date: 5 Dec 1837
Robert ROBERTSON
Brompton Row
Age: 31
Parish or Poor Law Union: Brompton Holy Trinity
Borough: Kensington and Chelsea
I wish I could find a marriage for Robert and Mary that would fit
