You are right that the children were all born in Illinois, except in the 1870 census they said Providence (then age 9) was born in Iowa.I found these censuses:
1870 Bloomfield, Davis, Iowa
1880 Trenton, Henry, Iowa
1885 Iowa census Trenton, Henry, Iowa.
So I think they moved to Iowa about 1860.
I haven't been able to find them in earlier censuses.I've even searched on just first names, thinking maybe "Huddleston" got scrambled by the census taker, but no luck.I found a Berry Huddleston in 1840 in Tazewell Co, Ill, but he is too old and there are a wife and some older children with him.Perhaps "our" guy was living with someone else before 1870.There are dozens of Kentucky Huddlestons who served in the Civil War, but not our guy.
Here are the details for the censuses I did find, if you don't have them:
1870 US census, Bloomfield, Davis, Iowa; image 31/66; 4 Jun 1870.
Dwelling & family 242.
Greenberry Huddleston, 54, laborer, b Kentucky
Sarah“, 53, Keeping house, Ohio
Alfred E.“, 24, brick maker, Illinois
Milton“, 21, brick maker, Illinois
Samuel F.“, 14, brick maker, Illinois
John S.“, 12, Illinois
Providence“, 9, Iowa
Hannah C. Gant, 24, Tennessee
Newton“, 2, M, Iowa.
1880 US census, Trenton Twp. Henry, Iowa; 17 Jun 1880; image 22/28.
Dwelling & family 236.
G. B. Huddleston, 63, farmer, b Kentucky, father bKentucky, mother b Kentucky, cannot read or write
Mary“, 62, keeping house, Ohio, Virginia, Virginia
Samuel“, 24, Illinois, Kentucky, Ohio, cannot read or write
John“, 22, Illinois, Kentucky, Ohio, cannot read or write
Dwelling and family 237.
Milton Hudleston, 31, Illinois, Kentucky, Ohio, cannot read or write, farmer
Loisa“, 24, Iowa, Ohio, Ohio, keeping house
Samuel“, 2, Iowa, Ohio
Rosey“, 11/365, b in May (prob 20 May).
1885 Iowa state census, Trenton, Henry, Iowa
Dwelling 115, family 121.
Green Huddleston, twp 72, range 7, section 31, NE SE, age 66, farmer, b Kentucky, native parents, eligible to vote
Sarah“, 65, keeping house, b Ohio, parents natural born citizens
John“, 24, farmer, b Illinois, subject to military duty
Dwelling 119, family 126.
Samuel Huddleston, 27, farmer, Illinois
Elizabeth“, 24, keeping house
(Sorry this is so long)I was working on this line for a friend and have sort of forgotten what we were doing.Do you have some ancestry for Sarah Merrifield?Because I have a few generations I could share.