The daughter who married Joseph HART was Jane ONAN, not "Iona" ONAN.
Joseph HART died 22 Mar 1846 in Hardin Co., KY. We then find Widow Jane (ONAN) HEART living with her parents in the 1850 Census of Knox Co., IL, and then in the same location in 1860 with her widowed mother. Jane's brother J. Hamilton ONAN is also living with them in the 1850 and 1860 censuses; he is age 30 in the former and age 40 in the latter. There's no sign of his having married.
John ONAN & Rebecca CARRICO married 2 Aug 1813 in Shelby [now Spencer] Co., KY. They are then found in the 1820 and 1830 censuses of Shelby/Spencer Co., KY, then the 1840 census of Hardin Co., KY, then the 1850 and 1860 censuses of Knox Co., IL. These censuses show John & Rebecca to have had these children (all born in KY):
01. (Daughter A) ONAN, b. 1813-15
02. (Daughter B) ONAN, b. 1815-20
03. (Daughter C) ONAN, b. 1815-20
04. (Daughter D) ONAN, b. 1815-20
05. J. Hamilton ONAN, b. 1819/20
06. Jane ONAN, b. 1821/2
07. (Son A) ONAN, b. 1820-25, prob. ca. 1824
08. Martha ONAN, b. 1826/7
09. Margaret ONAN, b. 1830/1
10. Elizabeth ONAN, b. 1834/5
"Son A" must be James.
Everything I have is online at my web site in the form of linked family group sheets, which you can hook into from John & Rebecca's page:http://dgmweb.net/genealogy/FGS/O/ONanJohn-RebeccaCarrico.sh...
I'm afraid I have no information beyond what is online. If anyone feels I've made any errors, please don't hesitate to correct me. My interest here is CARRICO. I'm just trying to fill out Rebecca's family group sheet.