After learning that he was terminally ill, Roger took his own group of pirates to conquer the Great Passage, and after reaching Ravdru, Roger learned many secrets. But Roger also understood that he was not the chosen one who could fulfill the great historical mission, because Roger said that they came early, and the younger generation was the one who could complete the historical mission. Roger disbanded his pirate regiment and chose to surrender himself to the Navy, but he has made arrangements accordingly, and the following 5 people may have been instructed by Roger.
Riley
Roger had given Reilly some words before disembarking, but people didn't know what Roger had said to Reilly. Reilly is Roger's right-hand man, Roger's unfulfilled will, Reilly will definitely help Roger to achieve. Perhaps roger's account to Reilly was to protect and nurture his heir, and the straw hat he gave to Shanks was the carrier of Roger's will. So when Luffy in the straw hat appeared, Reilly knew that Luffy was the object he needed to protect and cultivate.
Shanks
After Roger returned from Rav Drew, Shanks asked Roger some questions, then threw himself into Roger's arms and cried. Was Shanks also instructed by Roger? What exactly should Roger's heir choose may be a question shanks needs to consider, and when Shanks meets Luffy, he finds the answer. So Shanks will guide Luffy to become a pirate, and give the straw hat to Luffy for safekeeping, and when Luffy is qualified to complete the historical mission, he can return the straw hat to Shanks.
oden
Mita was also Roger's right-hand man, and his adventures with Roger were recorded in his diary, perhaps with Roger's advice after his return. When Mita was about to enter the Kingdom of Wano, he said that it was necessary to let the Kingdom of Peace be opened before the next "Joy Boy" arrived in the Kingdom of Peace, and I don't know if this Joy Boy was directing the way, and did Lady Shi foresee that there would be a great war in the Kingdom of Peace more than twenty years later? Perhaps Roger's instructions to Oda were to help Roger's heirs point the way to Ravdru, but Mita lost to Kaido and did not fulfill Roger's instructions.
Whitebeard
After Getting off the boat, Roger goes to meet Whitebeard, and the two have a drink together, and Roger wants to tell Whitebeard the route to Rav Drew, but Whitebeard says he is not interested. Roger came to see Whitebeard, and perhaps asked Whitebeard to help protect Fishman Island, protecting The Sea King from being harmed by humans, because the Sea King is an important factor in fulfilling the great historical mission.
Karp
Before his death, Roger asked Karp to take care of his son in prison, and Karp did the same, and he managed to protect Ace. Roger also mentioned his son before he died, and had high hopes for him, but Ace did not want to live as his father expected, Ace wanted Whitebeard to become One Piece, but Whitebeard himself did not want to become One Piece.
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