Previously a direct line male was required for DNA testing. But now with autosomal DNA "Family Finder" at Family Tree DNA. Direct line females can also work. Pedigree lines back to the GGrandfathers are very helpful.
Since the Lewis and Hugh lines are represented at the Branam Surname DNA Project too, you may want to consider Branham, Branam, and Branum along with your Brandon spelling. The Bran??? in the Tan group were listed in census records under a variety of spellings both in Roane Co., TN and Alabama.