Mystery Monday - Vanishing Father

Nancy L Logan was born 29 November 1825 in Tennessee to Tarlton L Logan born 7 January 1803 and Jane Campbell born 9 January 1800.  Tarlton moved his family to Holly Springs, Marshall County, Mississippi between 1833 and 1836.  They didn't stay long and went up the Mississippi River to the White River and then up the James River to Greene County, Missouri.  This is where Nancy met and married (James) Thomas Hedrick on the 8th of October 1852.  Their only child, William Cowdry Hedrick was born on 23 November 1853.  In the 1860 census, Nancy and William are living in her parents household.  I have never been able to find Thomas in any census record.  I know absolutely nothing about him.  William married Nancy Mehitable Hazelton in Greene County, Missouri.  They moved to Stafford County, Kansas in 1886 and then on to Oklahoma Territory in 1895.  I visited with my grandmother about Thomas and she recalled the story that Thomas had another family.  I discovered an interesting census record:

name:	William G. Hedrick
residence:	Pond Creek, Greene, Missouri
birthdate:	1855
birthplace:	Missouri, United States
relationship to head:	Self
spouse's name:	Nancy Hedrick
spouse's birthplace:	Missouri, United States
father's name:
father's birthplace:	Tennessee, United States
mother's name:	Nancy Hedrick
mother's birthplace:	Tennessee, United States
race or color (expanded):	White
ethnicity (standardized):	American
gender:	Male
martial status:	Married
age (expanded):	25 years
occupation:	Farmer
nara film number:	T9-0687
page:	149
page character:	C
entry number:	4695
film number:	1254687
	Household	Gender	Age	Birthplace
self	William G. Hedrick	M	25	Missouri, United States
wife	Nancy Hedrick	F	23	Missouri, United States
son	Rily Hedrick	M	2	Missouri, United States
moth	Nancy Hedrick	F	54	Tennessee, United States
bro	Charley Hedrick	M	15	Missouri, United States
sis	Satola Hedrick	F	13	Missouri, United States

Source Citation

"United States Census, 1880," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/M6X3-QVQ : accessed 03 Sep 2012), William G. Hedrick, Pond Creek, Greene, Missouri; citing sheet 149C, family 0, NARA microfilm publication T9-0687.

I tried to find Charley or Satola in previous census years, but came up empty.  I did find a Charley H Hedrick in the 1920 census in Ray County, Missouri with a son named James T Hedrick.   I theorize these are the same Charley's.  The difficulty in finding Thomas Hedrick, I have no clue as to his age when he married Nancy Logan.  The census has always been consistent regarding the birthplace of Thomas as being Tennessee.

I am really curious about 3 things; 1. where is Thomas?; 2. how did these children come to live with William in 1860? and 3. who was the mother of these children?

Can you help me break down this brick wall?