Complex sentence: Anderson's brother, Charles, had changed his name to Anderson-Pelham when he succeeded to the estates of an uncle in 1763 and also had an interest in the parliamentary seats at Grimsby and at Beverley.
Split into simpler sentences: Anderson's brother Charles had changed his name to Anderson-Pelham when he succeeded to the estates of an uncle in 1763. He also had an interest in the parliamentary seats at Grimsby and at Beverley.