Dumah
Parents: Ishmael.
Siblings: Nebajoth, Kedar, Adbeel, Mibsam, Mishma, Massa, Hadar, Tema, Jetur, Naphish, and Kedemah.
Other: Isaiah 21:11 (and the sub-title above that passage in my Study Bible) suggests that Dumah is also Seir...whether this refers to the man or the country named for him, I do not know.