I'm presently working on this area and have learned that this Harrison clan generated quite a few preachers. Franklin Pierce Harrison, son of William "Grand Sir" Harrison, Bama Lavonia Harrison, and Millard Franklin Harrison, children of Franklin Pierce Harrison were all ministers. I have daily contact with Millard Harrison who will soon be approaching his 94th birthday. He lives in Bartow, FL.
Also the son of Mathis Harrison and Ada Phillips (James Ruhane Harrison) is also a practicing minister today in Auburndale, FL.