“It’s exciting when Trump comes into town, isn’t it?” Eric Trump declared Wednesday evening amid the festivities.

Not just Trump, but the Trumps — decidedly plural. As the president has hopscotched on official duties between three European nations this week, his four adult children — also including daughters Ivanka and Tiffany — have been prominently involved in many high-profile moments.

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They sat for the white-tie dinner with Queen Elizabeth, toured the Churchill War Rooms, attended the 75th anniversary commemoration of the D-Day invasion in Normandy and, for the Trump sons, checked in on the family business at Trump International Golf Links & Hotel in Doonbeg, where the president is spending two nights before returning to Washington on Friday.

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If the display sought to project the Trumps as global goodwill ambassadors for the United States, it has also raised questions given the president’s refusal to draw strict boundaries between his official duties and his private business.

Ivanka and her husband, Jared Kushner, hold administration jobs, while Trump’s two eldest sons oversee the Trump Organization’s real estate holdings around the world, including the Doonbeg property. Lara Trump, Eric’s wife, who is also on the trip, is an adviser to the president’s campaign. Barron, Trump’s 13-year-old son, remained in Washington.

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The question of who is paying for the family members’ participation — and whether American taxpayers will be on the hook — has emerged as an unresolved subplot, with newspapers in Scotland and London scouring State Department databases and reporting on the fancy hotels and expensive limousines contracted by the U.S. government.

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During the trip, the Trump children have documented their exploits in Instagram posts — touring Buckingham Palace! observing the aerial flyover in Normandy! pouring pints behind the bar in Doonbeg! — in a modern-day slide show of “wish-you-were-here!” family vacation moments for the public back home. At times, the images appeared discordant with the aims of a U.S. government delegation representing the nation’s geostrategic interests.

“Questions surrounding the family on this trip come from Trump’s decision not to divest from his business and hiring Ivanka and Jared,” said John Wonderlich, executive director of the Sunlight Foundation, an open-government advocacy group that has sought to document potential conflicts of interest for the Trump family.

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“It’s not utterly inappropriate for family members to be involved in a state dinner, but are they trying to show they are united and that the business and family interests are the same?” Wonderlich said. “We’re always left in doubt about what their intentions are. You can’t say it’s just a family.”

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Trump aides scoffed at such questions and privately pointed out that past presidents have traveled with family members, including children. Presidents Barack Obama and George W. Bush brought their children on some foreign trips, and former aides said there was nothing inherently untoward about such arrangements.

In 2013, for example, the Obamas brought daughters Malia and Sasha — both minors — on a three-nation tour of Africa, including a family visit to Robben Island, where Nelson Mandela had spent almost two decades in prison. In 2002, first lady Laura Bush brought one of her twin daughters, Jenna, then in college, on an official government trip to three European nations.

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Presidential children raise the public costs of a trip, given that they require Secret Service protection, but it is less clear how many other expenses would be incurred by taxpayers, former government officials said. First lady Melania Trump, who is also on the trip, has an official government role, as do Ivanka Trump, 37, and Kushner, 38, who are senior White House advisers.

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But Donald Jr., 41; Eric, 35; Tiffany, 25; and Lara Trump, 36, fall into a nebulous category — especially the two sons, said Jeff Rathke, who served 24 years as a Foreign Service officer in the State Department.

“The president remains the owner of the Trump Organization, but his adult sons are running the business,” Rathke said. “It would seem to me that this would be a classic case where an agency ethics official would have to weigh in on whether it is appropriate for the adult children’s travel to be covered or require reimbursement.”

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The Trump children did not travel on Air Force One to London for the president’s three-day state visit. Reporters traveling on the presidential plane also did not spot Donald Jr. or Eric on board as the president made a round-trip flight from Ireland to Normandy for the commemoration ceremony — although both sons were present for the program.

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“Words cannot describe the experience on being here on the site of one of the most significant battles in history,” Donald Jr. wrote in a caption to photos of the event on Instagram.

White House officials declined to comment.

Former government officials said family members traditionally are not involved in bilateral meetings but often participate in cultural events. The Trump children were present at the state dinner with the queen and a black-tie dinner in honor of Prince Charles at Winfield House, the residence of U.S. Ambassador Woody Johnson.

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Ivanka Trump was at the table with the president, Treasury Secretary Steven Mnuchin, Prince Andrew and Prime Minister Theresa May when they met with American and British business leaders. She highlighted that discussion on Instagram between a photo of the Trump children posing in a bunker used by Winston Churchill during World War II and a shot of Kushner and her gazing from a window at Buckingham Palace.

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Ivanka then peeled off to represent the administration at the Global Entrepreneurship Summit in The Hague.

In London, President Trump spent his nights at Winfield House, reportedly because Buckingham Palace is undergoing renovations.

Trump’s aides stayed in some of the toniest neighborhoods in London, with rates for standard hotel rooms at the Intercontinental Hotel Park Lane easily topping $500. On May 20, the State Department submitted an order for the hotel for more than $1.2 million, according to federal government spending data first reported by a Scottish newspaper, the Scotsman, and the Guardian.

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Chauffeured cars outside the U.S. ambassador’s residence in London included several late-model Range Rover SUVs, which retail at above $100,000 each.

It has not been publicly disclosed where the Trump children stayed.

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Before he became president, Trump regularly criticized Barack Obama and his family for their travel costs.

“The Obama’s Spain vacation cost taxpayers over $476K,” Trump tweeted on April 27, 2012, citing federal figures compiled by the conservative group Judicial Watch. “They love to spend money.”

Tim O’Brien, author of Trump biography “TrumpNation: The Art of Being the Donald,” said the president is potentially trying to set his children up for political futures of their own.

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“Donald Trump’s entire experience — as a business person in the world and as a resident of New York growing up in his own father’s business — was that you acquired relationships, and money and success through access,” O’Brien said. “And he’s giving his children all of the advantage of access that he can as president of the United States.”

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Ahead of the trip, a British government official, briefing reporters on background, said the May government was “flattered” that Trump’s family wanted to take part in the visit, suggesting it was a sign of the strength of the bilateral relationship.

In Doonbeg, a tiny costal village of fewer than 1,000 on the western edge of Ireland, locals were thrilled to see the Trump sons as they meandered through five local pubs Wednesday and poured drafts for patrons, with reporters in tow.

“Does Doonbeg love the Trumps?” the brothers shouted, prompting affirmative cheers.

“It was huge publicity for Doonbeg. No one had heard of us, and now all of a sudden it’s been shouted around the world,” marveled Caroline Kennedy, owner of the Igoe Inn. Of the president, she added: “He’s a good businessman. Every time he mentioned he would come down, Doonbeg got a mention.”

For the Trumps, it was a rare chance to revel outside the harsh gaze that has accompanied their father’s itinerary. Thousands protested the president’s visit to London, while thousands more demonstrated in Dublin.

Asked if the Trump sons talked politics, Hugh McNally, owner of Morrissey’s pub, scoffed.

“These boys were on a holiday over here,” he replied.