@Sir James of Grange and @Janet Melville, daughter of Sir James Melville of Raith had the following children:
Five sons only:
1. @Sir William Kirkcaldy, of Grange, Governor of Edinburgh Castle, d. 3 Aug 1573, Mercat Cross, Edinburgh, Scotland Find all individuals with events at this location
2. (A brother) @Sir James Kirkcaldy, of Grange, b. Abt 1530, d. hanged on the same scaffold with Sir William in 1573
3. @David Kirkcaldy
4. (A brother) @Thomas Kirkcaldy, b. Abt 1530, d. 3 Aug 1573, Mercat Cross, Edinburgh, Scotland Find all individuals with events at this location (Age ~ 43 years)
5. @George Kirkcaldy
Four daughters only:
1. (A sister) @Marjory Kirkcaldy married @Harry Ramsay younger of Colluthie
2. (A sister) @Agnes Kirkcaldy married @Robert Drummond of Carnock, Master of Work to the Crown of Scotland
3. (A sister) @Marion Kirkcaldy married @William Semple, second baron of Cathcart;
4. (A sister) @Elizabeth Kirkcaldy married @Sir John Mowbray of Barnbougle
I find that this information from Dictionary of National Biography, 1885-1900, Volume 31 by Thomas Finlayson Henderson seems quite credible. Isobell is not listed among the daughters and @William Ferguson is not listed as being among the son-in-laws.
Reference: https://en.wikisource.org/wiki/Kirkcaldy,_James_(DNB00)
