Complex sentence: A major turning point in their relationship occurred on the family trip to Europe on the steamship Vanderbilt in 1860, after which, the two became very close and Billy was given a greater role in business matters.
Split into simpler sentences: A major turning point in their relationship occurred on the family trip to Europe on the steamship Vanderbilt in 1860. After which, the two became very close and Billy was given a greater role in business matters.