I'm always looking for BARTLETTs, particularly those from VA.This appears to indeed be a Floyd Co, VA family...
Reuben BARTLETT was in Montgomery Co, VA 1798 to 1830, then Floyd Co formed in 1831 and he is in Floyd 1840 census.His oldest son, Samuel BARTLETT b 1806 m 1831 Mahala THRASH.In 1850 Jackson Co, MO (Wash Twp) we find: Mahala BARTLETT 30 VA Sarah 19 VA Reuben 15 VA William 14 MO Lydia 9 MO Ann E 6 MO Robert 4 MO Samuel 1 MO
It looks like Mahala died before 1860 and Reuben, William, L (Lydia) and Robert were all in other families by 1860; as outlined in your post.(I'm not sure what family Margaret belongs to).
By the way Rueben above was the son of Garner BARTLETT who is believed to descend from the BERKLEYs of Loudoun Co, VA and Westmoreland Co, VA before that.We may be getting a BERKLEY descendant to participate in the BARTLETT DNA project - so we need some descendants of Garner BARTLETT to also join the DNA project so we can see if we have a match.