The are 3 marriages in Markethill registers. They show that George COMPSTON, a farmer had the following children:

Mary COMPSTON of full age in 1857 when she married Adam Allen. Her brother Robert was a witness

Robert COMPSTON was of full age in 1865 when he married Olivia Hanna

Samuel John COMPSTON was of full age in 1868 when he married Ann Eliza Jamison.

http://www.markethillpresbyterian.co.uk/2nd_marriages_1845_1919.htm

Marriage Register First Markethill 1845 -1919 COMPSTON

When Married Name and Surname Age Condition Rank or Profession Residence at time of Marriage Father's Name and Surname

11 June 1857 Adam Allen Full age Batchelor Farmer Derryrain William Allen Farmer witness Robert Compston Rev Robert Morrison
Mary Compston Full age Spinster Drumachee George Compston Farmer William Hooks

4 August 1865 Robert Compston Full age Widower Mechanic Crumlin George Compston Olivia Hanna Full age Spinster Drumahee John Hanna
Witnesses Samuel John Compston Mary Hanna

7 February 1868 Samuel John Compston Full Age Bachelor Labourer Drumahee George Compston Labourer William McStay Rev Robert Mitchell
  Ann Eliza Jamison Full Age Spinster Retarnet James Jamison Joiner Mary Jamison

BIRTHS First Markethill 1845 -1919

13 July 1862 William George, to Adam Allen and Mary Compston, born 22 March 1862

16 April 1867 Lucinda, to Robert Compston and Susan Hannah, born 30 December 1866

4 April 1869 Robert, to Adam Allen and Mary Compston, born 16 October 1868

7 November 1870 Maggie, to Robert Compston and Susan Hannah, born 21 July 1870

16 March 1874 Eliza, to Adam Allen and Mary Compston, born 13 August 1873

Sarah Mary Compston Samuel Compston Farmer Drumattee Ann Eliza Jamison Drumattee 27 November 1868

Robert Compston Samuel Compston Farmer Poke Mill Poke Mill 16 February 1871

James Compston Robert Compston Farmer Poke Mill Susan Hannah Poke Mill 24 July 1872

George Compston Samuel J. Compston Farmer Poke Mill Poke Mill 25 March 1875

 Samuel Compston Samuel J. Compston Farmer Poke Mill Poke Mill 20 October 1877

Sarah Margaret Compston Robert Compston Farmer Poke Mill Susan Hannah Poke Mill 20

William John Compston Samuel J. Compston Farmer Poke Mill Poke Mill 8 January 1880

 Jane Compston 26 NOV 1873 , Armagh, Robert Compston Mother: Olivia Hanna

GEORGE COMPSTON 01 JUN 1866 , Antrim, ROBERT COMPSTON Mother: OLIVIA HANNA
 JOHN ROBERT COMPSTON 09 OCT 1868 , Armagh, ROBERT COMPSTON Mother: OLIVIA HANNA
SAMUEL DAVID CUMPSTON  08 JAN 1870 , Armagh, ROBERT CUMPSTON Mother: OLIVIA HANNA
Sarah Margaret Compston 20 DEC 1876 Armagh, Armagh, Robert Compston   Mother: Susan Compston Hanna
George Compston Birth: 23 MAR 1875 , Armagh, Samuel John Compston Mother: Anne Eliza Jameson
James Compston Birth: 24 JUL 1872 , Armagh, Robert Compston Mother: Susan Hanna
John Compston Birth: 08 FEB 1880 Drumahee, Armagh, Samuel John Compston Mother: Anne Eliza Compston Jameson
ROBERT COMPSTON Birth: 16 FEB 1871 , Armagh, SAMUEL JOHN COMPSTON Mother: ANNE ELIZA JAMESON
James Compston Birth: 24 JUL 1872 , Robert Compston Mother: Susan Hanna

George Compston Birth: 23 MAR 1875 , Samuel John Compston Mother Anne Eliza Jameson

COMPSTON 30 DEC 1866 0073, Market Hill, Armagh, ROBERT COMPSTON Mother SUSAN HANNA 

DETAILS OF THIS FAMILY

First Markethill 1845 -1919

GEORGE COMPSTON 01 JUN 1866 , Antrim, ROBERT COMPSTON Mother: OLIVIA HANNA

COMPSTON 30 DEC 1866 0073, Market Hill, Armagh, ROBERT COMPSTON Mother SUSAN HANNA 

DEATH 16 April 1867 Lucinda, to Robert Compston and Susan Hannah, born 30 December 1866

Sarah Mary Compston Samuel Compston Farmer Drumattee Ann Eliza Jamison Drumattee 27 November 1868

JOHN ROBERT COMPSTON 09 OCT 1868 Armagh, ROBERT COMPSTON Mother: OLIVIA HANNA

MARGARET COMPSTON 21 JUL 1870 Armagh, ROBERT COMPSTON Mother SUSAN HANNA. DEATH 7 November 1870 Maggie, to Robert Compston and Susan Hannah, born 21 July 1870

SAMUEL DAVID CUMPSTON  08 JAN 1870 Armagh, ROBERT CUMPSTON Mother: OLIVIA HANNA
 
ROBERT COMPSTON Birth: 16 FEB 1871 Armagh, SAMUEL JOHN COMPSTON Mother: ANNE ELIZA JAMESON Farmer Poke Mill

James Compston Birth: 24 JUL 1872 Armagh,  Robert Compston Mother: Susan Hanna

Jane Compston 26 NOV 1873 , Armagh, Robert Compston Mother: Olivia Hanna

16 March 1874 Eliza, to Adam Allen and Mary Compston, born 13 August 1873

George Compston Birth: 23 MAR 1875 , Armagh, Samuel John Compston Mother: Anne Eliza
Jameson DEATH George Compston Samuel J. Compston Farmer Poke Mill Poke Mill 25 March 1875
 
Sarah Margaret Compston 20 DEC 1876 Armagh, Robert Compston   Mother: Susan Compston Hanna Sarah Margaret Compston Robert Compston Farmer Poke Mill Susan Hannah Poke Mill DEATH 20 December 1877

Samuel Compston Samuel J. Compston Farmer Poke Mill Poke Mill DEATH 20 October 1877

John Compston Birth: 08 FEB 1880 Drumahee, Armagh, Samuel John Compston Mother: Anne Eliza Compston Jameson