This had caused considerable animosity between Baldwin IV , Count of Flanders and Eustace 's father , but when Baldwin IV 's son Baldwin V succeeded him in 1035 Eustace I and Baldwin V of Flanders cooperated on several ventures including several charters and in limiting the powers of the Castellan-advocates of several abbeys including the Abbey of Saint Bertin in Flanders .
When Baldwin IV 's son Baldwin V succeeded him in 1035 Eustace I and Baldwin V of Flanders cooperated on several ventures including several charters .