Speculation about how his grandson Bernard of Septimania came to be described as sharing the blood of the Carolingian rulers has led to hypotheses regarding Theuderic's ancestry.
A donation she executed was witnessed first by her only son, Charibert, and then by Bernarius, Chrodlanda and Theoderic.
The last of the witnesses of Bertrada of Prüm's donation, Theoderic, is suggested either to be one and the same with Thierry, or else his father.
[3] A second possible avenue for a relationship comes via Theoderic's wife, Aldana, whose parentage is not directly documented but who had known sisters, Hiltrudis and Landrada.
Theodoric V is given to T'erric Tirel, the grandson of Nivelon IV, and brother of Waleran de Vexin.