I can tell you that your Preston Beck acquired land in Shawswick Twp, Lawrence Co., INApr 14, 1818.
NE 1/4 Sect 14, Twp 5N, R1W
This information comes from the abstract of my mother's current property in the city of Bedford.
As for Decker Twp - I have never seen it mentioned except on the 1820 census. Goodspeeds 1884 History of Lawrence county, which goes into detail about the formation of the townships of the county makes no mention of any Decker Twp ever existing. The name Decker is not among those on the 1820 census index for Lawrence or any surrounding counties. This remains a mystery......