Complex sentence: Berengar I of Neustria was Marquis of Neustria, relative of Adalard the Seneschal and Udo of Neustria, Girardids close to the Conradines and probably father of Berengar II of Neustria.
Split into simpler sentences: Berengar I of Neustria was Marquis of Neustria, one of the Conradines along with Udo of Neustria to be cousins of Adalard the Seneschal, a Girardid. Berengar was probably father of Berengar II of Neustria.