Well, its possible,because of the names Allen,simpson and Ky you mention,so heres some info that MIGHT be related. I am of the Johnstons who lived in Tullahoma Tn 1810 to 1862 then Johnstons and simpsons in ky 1862 to 1880s then Johnstons and simpsons lived in ark 1885 to 1935 The Allens of Tullahoma Tn married into the Johnston family( 4 Allen bros married 4 Johnston sisters when in Tn probably 1840 to 62 is my guess). My GGF ,Lewis Johnston b 1857 in Tn,married a Irene Simpson who originally lived in Ohio Co Ky and were friends of the Ky Johnstons. In 1906 The Johnstons and simpsons had their last known get together when they lived as neighbors in Siever Co ark. near the Cossotott (sp?) river where many of both family members are buried. Called Cossatot cemetary West ark,just NNE of ft smith . I gave you all the information in general that I recall from papers (letters,bible,and other docs)I had in 2005. Anyone of the details could each lead you to a connection. Hope you find something useful
John Johnston