Complex sentence: In real life, it has been reported that Melvin Weinberg began working for his father only as an adult, and that he did smash windows, however at the behest of the local union, to punish businesses who used non-union glaziers.
Split into simpler sentences: In real life, Melvin Weinberg began working for his father only as an adult. A later report, however, states that it was done at the behest of the local union, to punish businesses who used non-union glaziers.