The following Graf Friedrich [II] is recorded in 1025 (as the father of Berthold [I]), in 1027 (twice, once as father of Otto [I]), and in 1030. He was therefore presumably a different person from Graf Friedrich [I], who is recorded as having died in Jerusalem before 1020. It is not known how the two Grafen Friedrich may have been related, if at all. However, the continuity of references to Diessen suggests a close connection, maybe father and son. Wegener conflates Graf Friedrich [I] and Graf Friedrich [II] as he appears to ignore the reference to the death of the former before 1020[223]. The De Fundatoribus Monasterii Diessenses does not name a second Graf Friedrich, although this is not surprising considering that it appears to ignore the generations between Graf Friedrich [I] and Otto Graf von Wolfratshausen[224]. Generally, the reconstruction of the family of the Grafen von Diessen is hindered rather than helped by the speculative connections suggested by Wegener. An attempt has been made in the following passages to explain these speculations and highlight any contradictions with primary sources which he does not cite. Unfortunately, it appears that many of these misleading speculations have found their way into the tables in Europäische Stammtafeln in which they appear as definite. In the case of this family, therefore, it is more important than ever to use the "back to basics" approach and start again from scratch in compiling information from primary sources. Hopefully, the results are relatively accurate but it is admitted that it is particular challenging to achieve a definitive reconstruction of this family and no doubt further improvements are possible.
1. FRIEDRICH [II] (-1030 or after). "Chonradus…Romanorum imperator augustus" donated property "forestum Hesilinestuda…iuxta villam Garza ubi ille rivus Inum fluvium influit…usque ad Pikkilinstein in comitatu Friderici" to the church of Salzburg by charter dated 7 Jul 1027[225]. Wegener quotes a reference to Graf Friedrich and his son Friedrich dated [1030][226]. m ---. The name of Friedrich's wife is not known. Graf Friedrich [II] & his wife had [five] children