Theobald's name occurs commonly in the "Codex of Salzburg" (Salzburger Verbrüderungsbuch) of 784. Theobald married Biltrude as his first or second wife. He may have had a prior marriage to one Waldrada, who conversely may have been his younger brother Tassilo's wife. Biltrude later married Grimoald, his youngest brother and successor.
