On 27 Nov 1820, he bought 60 acres in Lot 10, Front Con., Charlotteville Twp. from his father (Deed #1112). He next lived at Walsingham Twp. on 29 Apr 1823 when he bought 100 acres in Lot 27, Con. 1, Bayham Twp., Elgin Co. (Deed #64). Eliza was living with her son Calvin in the 1852 Census of Bayham Twp. They possibly had more than the five children listed for this marriage.
From The Loyalists in Ontario comes the note:
"Barnum.. Nathaniel Bunnell, settled Charlotteville, his children
1. David Wheeler Barnum, got his O.C.4 Dec 1834
2. Charles D Barnum O.C. 17 Oct 1839
3. Thomas Arnold Barnum, O.C 28 Jan 1841
4. Lois Green Barnum m. William Kimber, O.C. 3 Oct 1833
5. Henry V Barnum, O.C. 10 Mar 1834
6. James Russell Barnum, O.C. 10 Mar 1834
7. Christina Barnum m. Henry Liger, of Woodhouse, O.C. 7 Feb 1833
8. Andrew Wilson Barnum of Bayham, O.C. 22 Dec 1832
9. Samantha M Barnum m. James Clark of Walsingham, O.C. 6 Feb 1828
O.C. stands for "Order in Council", which means that they were now either married (if female) or over age 21, and could then claim their free land grant as a child of a Loyalist. In the case of males, it gives you a good idea of when they were born. All those with no location given were in Charlotteville, near their father.