The primary source which identifies Adalhard [IV] as the son of Adalhard [III] has not yet been identified. However, the Catalogus abbatem Epternacensium names "Adelardus iunior comes" as [lay] abbot of Echternach in 878 until 890, suggesting that he may have had the same name as his father. "Hludowicus…rex" confirmed a donation of property "in pago Muselahgeuui in comitatu Adalhardi villam…Berge" to Kloster Fulda by charter dated 24 Jul 880. Emperor Karl III granted property "in Weitereiba in comitatu Adalhardi ad Rosbach" to Kloster Fulda by charter dated 7 Apr 884.
The Liber Memorialis of Remiremont records the death "IV Non Jan" of "Adellardus", although it is not certain that this refers to Adalhard [IV]. 1