Complex sentence: Torrio and local "Unione Siciliana" boss Mike Merlo managed to get the Gennas to back down; however, since Torrio was allied with the Gennas, he refused to take any significant action against them.
Split into simpler sentences: Torrio and local "Unione Siciliana" boss Mike Merlo managed to get the Gennas to back off a bit. However, since Torrio was allied with the Gennas, he refused to take any significant action against them.