Elizabeth Myers who married John Evans and Barbary Ann Myers who married William Jones were probably sisters (the two families were on neighboring farms in 1860.) Her place of birth is listed as Montgomery Co. on the birth record for the twins Eli and Elias, and as Morgan Co. on the birth record for Jeff Davis.

A good possibility for their parents are Joseph Myers and Rachel Alfrey. They were the parents of Samuel Myers who married Emily Cassity, and that Samuel was also living very near the John Evans and William Jones families. (I should check Morgan County deed and estate records for prior ownership of these lots. One possibility is that a large farm was split among the surviving children.)

1850 census of Morgan Co., Ky, lists as family #237:
John Evans, 29; Elizabeth, 28; Isaac, 9; Mahala, 7; Joseph, 6; Rebecca, 5; David, 3. All born in Ky.

1860 census of Rowan Co., Ky, lists as family #272, between Wesley Byram and William Jones:
John Evans, 40; Elizabeth, 39; Rebecca, 15; David, 13; John T., 10; Henry, 8; Milton, 4; Eli, 1; Elias, 1. All born in Kentucky.

1870 census of Rowan Co., Ky, Pearce precinct, lists as family #32:
Evans, John, 49, farmer; Elizabeth, 48; Henry, 17; Milton, 14; Elias, 11; Eli, 11 (bracketed as twins); Jeff Davis, 8. All born in Kentucky.

1880 census of Bath Co., Ky, White Sulphur precinct, enumerated 17 June, lists on p. 19 as household #162, family #167:
Ivens, John A, 61, farmer; Elizabeth, 60, wife; Henry, 25, son; Elias, 20, son; Jeferson D., 18, son. John born Ky PA Ky, all others born Ky Ky Ky. (The next household is that of their son Eli.)