There are two George Knipp/Nipp's below. George #1 is the one who moved to Indiana; George #2 is the one who moved to Kentucky. If not numbered, we don't know which one it is.

There are two John Nipp's below. One is in George's generation (a brother?), and one is George's son.

1765 -  Verner Knipp born in Germany.
1773 -  George Knipp #1 born in Pennsylvania.
1775 -  Philip Knipp born in Pennsylvania.
1780 -  (or 1790) George Knipp #2 born in Wythe County, Virginia.
1783 -  Verner and Christeener were married.
1785 -  Rebecca (Townsend?), wife of George Knipp #1, was born.
1790 -  George Knip in Pennsylvania census, Northumberland County.  There was one
        male age 16 or over (George?), 4 males under age 16 (born after 1774), and 
        3 females in the household.
1796 -  Verner Knipp was listed in the April 23, 1796 Wythe County Virginia tax
        records as having no slaves, three horses, and two males over age 16.
1800 -  Same George Knip as 1790; still in Pennsylvania, Northumberland County, 
        "Penns" township.  Could this be Phillip's father?
1807 -  John Nipp married Dolly Cleaves in Wythe County, Virginia. 
1809 -  George Knipp married Rebeccah Townsend, daughter of John 
        Townsend, in Wythe County, Virgina on Jan. 7, 1809.  Adam 
        Knipp was a surety.
1809 -  Catherine Knipp, daughter of Adam Knipp, married Simon Reagle
        on Jan. 9, 1809 in Wythe County, Virginia.  Varner Knipp was 
        a surety.
1810 -  Virginia Census, Wythe County, has Verner Knip, age over 44, wife over 44, 1 male 10-15,
        2 males 16-25, a female 10-15, and a female 16-25.
1810 -  Virginia Census, Wythe County, has George Nipp, age 16-25, with 2 females & 1 male all under
        age 10 in the household:  Could be Nancy, Jane, and  John (b. 1811) named in the biog. sketch.
1810 -  Virginia Census, Wythe County, has John Nipp, age 16-25 with 1 female under 10.
        NOTE:  This John Nipp does not show up in any records after this point, but he could have
        moved somewhere other than Ohio or Indiana in 1820.  
1811 -  John Nipp, son of George Nipp #1, was born Nov. 18, 1811 in Wythe County, Virginia (from
        John's biog. Sketch).
1812 -  George Nipp #1 was a soldier in the war of 1812 (according to biographical sketch).
1814 -  George Nipp #1 moved to Tennessee (according to biographical sketch)
1815 -  George Nipp #1 arrived at Connersville, Indiana (according to biographical sketch)
1815 -  Peggy Knipp, daughter of Adam Knipp, married George Kegley on Oct. 10, 1815 in Wythe
        County, Virginia.
1815 -  Barbara Nipp was born Dec. 17, 1815 in Wythe County, Virginia
1820 -  Indiana Census, Fayette County, Jackson Township has George Nipp #1 with 3 females under
        under 10, 1 male under 10, and 2 females 10-16.  This adds Martha and Anna to his list of
        children, but there is an extra female under age 10 who doesn't show up in the 1830 Census.
        Could this have been Barbara "taken in", maybe orphaned?
1820 -  Virginia Census, Wythe County, has Phillip Nipp, but he stayed in Virginia.
1820 -  Virginia Census, Wythe County, has Peter Nipp, but he stayed in Virginia.
1820 -  Virginia Census, Wythe County, has George Nipp.
1821 -  George Nipp #1 bought land in Rush County, Indiana  on Dec. 11, 1821.
1824 -  Nancy Nipp married Mathias Govee on Sept. 9, 1824 in Rush County, Indiana.
1825 -  George Nipp #1 sold 80 acres in Rush County, Indiana on June 18, 1825.
1830 -  Indiana Census, Rush County, has George Nipp #1, age 50-59.  2 females were age 10-14 and 1
        was 15-19.  Nancy married in 1824, so these children are probably John, Jane, Martha, Anna,
        William, Leonidas, and Reuben.  
        NOTE: Barbara was 14-15 years old.
1830 -  Indiana Census, Putnam County (Greencastle) has Edward Nipp, age 20-29, 1 daughter under 5,
        but too young to be Barbara's father.
1830 -  Phillip Nipp appointed guardian of children; might have married Nancy.
1831 -  Barbara Nipp supposedly arrived in Fayette County, Indiana (from obituary - see note below*)
1834 -  Anna Nipp married George Short on Mar. 9, 1834 in Rush County, Indiana.
1836 -  Barbara Nipp married David Hartzell May 15, 1836 in Fayette County, Indiana.
1836 -  John Nipp married Catherine Goodman on Sep. 15, 1836 in Rush County, Indiana.
1837 -  George Nipp #1 bought 80 acres in Rush County, Indiana on Jan. 16, 1837.
1837 -  Martha Nipp married Elkana Mullins on Dec. 28, 1837 in Rush County, Indiana.
1839 -  Verner Knipp died May 7, 1839 in Sinking Springs, Green County, Tennessee.
1840 -  Indiana Census, Rush County, Rushville Township has George Nipp #1, age 50-59.
1840 -  Indiana Census, Rush County, Union Township has John Nipp, age 20-29.
1841 -  George Nipp #1 sold 120 acres in Rush County, Indiana on Jan. 15, 1841.
1850 -  Indiana Census, Decatur County, Adams Township has George Nipp #1, age 76, with wife
        Rebecca, age 65, Elizabeth, age 41, and Reuben, age 19.
1850 -  Indiana Census, Rush County, Union Township has John Nipp, age 38, wife Catherine, age 34,
        along with Sarah age 10, James age 8, William age 7, Jane age 5, John age 10 months.
1850 -  Indiana Census, Decatur County, Adams Township, has Leonidas Nipp, age 21, and wife (?)
        Margaret, age 16.
1858 -  George Nipp #1 died July 1858 at son John's home after walking from New Castle (biog. Sketch).
1859 -  Rebecca (Townsend) Nipp died Jan. 1, 1859 in Rush County, Indiana.
1860 -  Sarah Nipps married William Hendricks on Sep. 27, 1860 in Rush County, Indiana.
1887 -  John Nipp died Sept. 13, 1887 in Rush County, Indiana.

* note on Barbara's arrival in Indiana according to her obituary:  
the statement on arriving "at the tender age of 15" was written in 
1880, and came from however wrote the obituary.  The bio sketch on 
James A. Hartsell simply says she came in childhood.