What is the fine-grained topic of the following text: In another historical first for Princess in this region, the ships were commandeered by two brothers - Captain Paolo Ravera at the helm of Sapphire Princess and his older brother Captain Stefano Ravera on Diamond Princess when both ships met in Phu My and Laem Chabang. Only return the topic.
Brothers commanding Princess cruise ships in Phu My and Laem Chabang.