Ms. Trump and Mr. Kushner wanted to control who could travel on trips funded by the State Department, Ms. Ward wrote, citing a source at the department. Ms. Trump also often requested to travel on Air Force planes when it was not appropriate. When Rex W. Tillerson, the former secretary of state, would deny the requests, the couple would invite along a cabinet secretary, often Treasury Secretary Steven Mnuchin, to get access to a plane.

Over the past two years, Mr. Trump has waffled on whether he wanted his children serving in his administration. When he hired John F. Kelly as his chief of staff, a move that Ms. Trump and Mr. Kushner supported at the time, he gave an early directive: “Get rid of my kids; get them back to New York.”

Mr. Trump complained, according to the book, that his children “didn’t know how to play the game” and generated cycles of bad press. Mr. Kelly responded that it would be difficult to fire them, but he and the president agreed that they would make life difficult enough to force the pair to offer their resignations, which the president would then accept.

Ms. Trump and Mr. Kushner, however, have outlasted those plans, and Mr. Trump’s desire for them to leave the West Wing has come and gone in waves, associates said. Mr. Kelly resigned in December, and the couple has only gained in power since his departure.

If there is sympathy in Ms. Ward’s book for her protagonists, it is found in explaining how they grew up. Ms. Trump, she wrote, was wealthy but isolated. When she went to tour Choate Rosemary Hall, the elite Connecticut boarding school where she would attend high school, Ms. Trump arrived in a white stretch limousine. But she emerged from the car all by herself. “No one was there with her,” said her tour guide, who remained anonymous in the book.

Mr. Kushner’s father, meanwhile, had been grooming his son since childhood to become his successor in the family real estate company, Kushner Companies. When Mr. Kushner went away to Harvard, Ms. Ward wrote, his parents had a business associate keep an eye on him — by taking him out for dinner and reporting back on his activities — to make sure he was not dating non-Jews or doing drugs.

When Mr. Kushner and Ms. Trump decided to get married, both sets of parents were skeptical. Ms. Trump eventually won over the Kushners with her commitment to a grueling religious conversion regimen and her apparent intense desire to become part of a close-knit family.

Mr. Trump, meanwhile, did not understand why his daughter had to change her religion for anyone, even though he liked Mr. Kushner. He would joke that Ms. Trump could have married Tom Brady, the quarterback for the New England Patriots, and once joked to Robert K. Kraft, the team’s owner, that “Jared is half the size of Tom Brady’s forearm.”