As always, good to work with the facts.
Also from
http://worldconnect.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=DESC&db=johnstrachantree&id=I906 as already linked, you have:
4 Edward McBay b: 26 Nov 1848 c: 3 Dec 1848 d: 7 Feb 1931
+ Martha Alexander c: 20 Jan 1850 d: 9 Oct 1936
5 Robert Alexander McBay b: 9 May 1869 d: Abt 1950
5 John McBay b: 28 Aug 1871 d: 31 Dec 1957
+ Ann L. Andrew b: 23 Oct 1874 d: 12 Jun 1899
6 Margaret Watt McBay b: 23 Dec 1898
+ David Longmuir b: 15 Sep 1895
5 James Alexander McBay b: 28 Aug 1871 d: 29 Jan 1872
5 Mary Ann McBay b: 3 Sep 1872 d: 19 Nov 1957
5 Edward McBay b: 28 Jan 1875 d: 1975
+ Mary Helen West b: Abt 1879
6 Catherine Mearns McBay b: 3 Oct 1903
5 David Davidson McBay b: 2 Jan 1878 d: 23 Jul 1900
5 Alexander McBay b: 26 Feb 1880
5
Andrew Mowatt McBay b: Abt 1882 d: Abt 1947 5 Catherine Findlay McBay b: 23 Sep 1884 d: 23 Nov 1889
5 Richard Davidson McBay b: Abt 1886
+ Isabella Taylor b: 29 May 1887
6 Torquil or Tapprale Murray Davidson McBay b: 15 Sep 1916 d: 1984
6 Francis John McBay b: 18 Jun 1920 d: 1982
6 Jessie Christine Isabella McBay b: 29 Sep 1924 d: 1999
+ David Nicoll b: Jun 1922 d: Mar 1999
6 Cecil McBay b: 16 Aug 1927
5 William Davidson McBay b: 24 Mar 1889
+ Mary Murray Middleton b: 2 Mar 1894
5 Catherine Findlay McBay b: Abt 1891 d: Abt 1984
5 Margaret Gove McBay b: 9 Jun 1893 d: 11 Dec 1894
Monica