Suggest research of Bates named Willis in Dearborn Co., In, and in Boone Co., KY
In 1816 records of Dearborn CO. IN, Willis Bates listed.
Boone Co.KY adjoined Dearborn Co., IN
BOONE CO., KY In 1819 tax records of Boone Co., KY, Willis Bates listed as white male age 21 plus - no land. In 1823, Willis Bates had 66 acres on waterway Garrison, as did one William Bates in Boone Co.,KY.William Bates a candidate brother from Madison Co., Virginia
There was a Willis Bates, who served in War of 1812 from KY. He served with "The Roll of Capt. John Duvall's Company of Infantry of the KY Militia. Willis Bates and William Bates were listed on the Militia Rolls.
Dependent upon further research this may be the "older" Willis Bates that you mentioned in your posting.
Indeed, William Bates d1794 in Madison Co., Virginia had as son Willis Bates of an age to be in War of 1812. This Willis Bates had a brother named William Bates, who may have been with Willis on the Militia Rolls.