Have put together the information I found in timeline format so you can see sequence of events. (the underlined bit will be explained later)
Lamont Carson Ormiston ANDREWS1870- grandfather Michael Andrews died (will, PRONI, 20 pages) The Will (with two Codicils) of Michael Andrews late of Ardoyne near Belfast County Antrim Linen Merchant and Damask Manufacturer deceased who died 20 December 1870 at same place was proved at Belfast by the oaths of William Walker of Banbridge County Down Linen Manufacturer and William Borthwick of Belfast aforesaid Merchant the Executors. (religion- Presbyterian) buried Clifton St. Cemetery
http://www.holycrossparishbelfast.com/history.htm1873, 17 June- parents James Ormiston Andrews & Jane Lamont married. Belfast Newsletter, 18 June 1873: ANDREWS-CARSON- June 17, at St. Anne’s parish church, Belfast, by the Rev. Dr. Hannay, James Ormiston, son of the late Michael Andrews, of Ardoyne, Belfast, to Jane Lamont, eldest daughter of the late Lamont Carson, of Belfast.
1874, 13 Mar., Argentina- brother Michael Lamont Ormiston Andrews born (d.1961 Texas)
1875, 19 Sept., Belfast- brother Thomas Corbitt Ormiston Andrews born (d.1954 Texas)
1877, 10 Feb., Belfast (birth registration Frederick Ormiston Andrews 10 Feb.1877 Ardoyne Cottage). Belfast Newsletter, 12 Feb.1877: ANDREWS- February 10, at The Cottage, Ardoyne, Belfast, the wife of J.S.[?] Andrews, of a son.
1881 Census- High St., Orsett, Essex, England: boarder Lamont C.O. Andrews, 4, Ireland. In household of Susannah Finch
?
c1885- parents separated
1902- Aug. “Gray Head” arr. Galveston, Tex. From Swansea, Wales: Lamont Andrews,
single, age 25y 6m, last res.- Belfast, civil engineer, in US 1901 Houston, going to mother in Houston.
?
1909, 2 Feb.- father James Ormiston Andrews d. Houston, Texas
1910 Census- Houston, Harris, Texas: Lamont Andrews, age 32, b.Ireland, married, to US 1902;
wife Josie Andrews, age 26, b.Ireland
1912, 8 Sept. (crossed out)- SS New York arrived NY from Southampton,
Josephine Andrews, to husband L. Andrews Yoakum Texas, 5’3” fair complexion fair hair blue eyes,
b. Dublin, mother Mrs. McNulty 65 Railway St Dublin
1912, 29 Sept. “St Louis” arr. NY from Southampton:
Josephine Andrews, 28,
b.Dublin, married, housewife, husband Lemont Andrews Yoakum Texas
1918 WWI draft registration card- Lamont Andrews, b.10 Feb.1877,
wife Josephine Andrews 15 Little Patrick St. Belfast?
1920, 27 Mar.- married Eudalia Loos
1935- Dewitt, Texas (according to 1940 census)
1940 Census- Houston, Harris, Texas: age 63, b.Ireland, Naturalized, safety inspector- PWA; wife Eulalia Andrews, 48, b.Texas.
?
1940, 30 Aug.- mother Jane Lamont Carson (b.30 Mar.1951 Ire.) died Joppa?
1964, 17 July: Lamont Andrews d.Cuero, Dewitt Co., Texas, age 87, b.10 Feb.1877 Ireland, retired railroad eng., married, res.- Yoakum Prec.6 Dewitt Co., bur. 19 July 1964 Hebron Cemetery (LDS- image), informant- Mrs. Eudelia Andrews (parents names not known), pneumonia
1976, 30 Mar.: Eudelia Andrews d.Yoakum, Lavaca Co., Tex., b.10 May 1892 Dewitt Tex, parents- Ignatz Loos + Elizabeth Hollan, wid., informant- Mrs. O.L. Rice. (LDS- image)
more to follow...