Complex sentence: He works at his father-in-law, Mr. Jacoby's (Holmes Osborne) bank, with meaningless, made up job, and his in-laws don't take him seriously, especially his brother-in-law.
Split into simpler sentences: He works at his father-in-law, Mr. Jacoby's (Holmes Osborne) bank. But his job is meaningless with a made up title, and his in-laws don't take him seriously, especially his brother-in-law.