There were three Isaac Creek's in Clay Co. Illinois aside from Isaac Creek Sr. who dies circa 1854.
A.Isaac Creek m. Rebecca A. Walston 06-06-1858 1850 this Isaac is found in the household of Isaac and his second wife Nancy Hoddy.Many have transcribed the name as Israel, but closer examination of the census takers handwriting and the age of 12 or thirteen indicates this is likely the same Isaac who's listed with his wife Rebecca and child Mary in the 1870 with an age of 23.They disappear after 1865 (They can be found in the state census living next to John Alexander Walston as in the 1860 census.) Mary E. Creek emerges in 1880 with her husband James Courtright.They marry in 1879.This is also a second marriage for James.It's also important to note Rebecca's sister and brother both married Creeks. John Alexander Walston m. Martha Ann Creek 03-30-1864Martha's name is transcribed incorrectly as Asenberech on the Illinois State Archives site.I've seen the original record on microfilm and it's most certainly Martha Ann Creek. Polly (Mary) A. Creek m. David Creek 06-03-1858 This is three days prior to her sister's marriage.This is also David's second marriage.
B.Isaac Creek m. Matlilda A. Quertemos 01-05-1866 I suspect this Isaac was the son of Jefferson and can be consistently followed through census records through 1910 where he's a widow in Missouri. 1860 age 19 Clay Co. 1870 age 28 Clay Co. 1880 in Kansas 38, 1900 in Missouri 59, and 1910 in Missouri 69.
C.Isaac Creek m. Elizabeth Partridge 12-20-1868 I've located one census record in Clay Co. for this Isaac in 1870 and his age is 23, he and his wife are also living next to a Partrigde family.