I carried your Samuel in my file for years until a descendant, an atty, in the Dallas, TX, area set me straight.But, I still have the info in my Alexander reference.
In Alexander Kin Vol II, pg. 446 (beginning of several pages)is family history for Samuel B. Alexander of Gibson Co., TN, who married Mary Sloan.[One source gives her name as Mary Ann Sloan]
They had some 10 children, the first one listed is James Sloan Alexander.He married Elizabeth Delasmut Elliott.Soon after, they moved to Maury Co., TN.In 1849, they moved to Hot Springs, AR, near Malvern.About 1885, they moved to Red River Co., TX, near Cut Hand where both eventually died and are buried.They had 12 children.Etc.
If interested, send me your email address and I will scan and send the several pages of the book.Samuel B. apparently had a bro. whose history is just a page or so before Samuel's:Josiah Martin Alexander.It seems that I recall coming to the conclusion that they were NOT in fact brothers, but brothers-in-law; i.e., marrying Sloan sisters.I do not have time now to re-read it now, but I am certain that the book is incorrect and they were b-i-l's and not brothers.They referred to b-i-l's as brothers often in those days.I can send his also.That would be pages 444-451 of the book. Regards, Mac Alexander, Cypress, TX.