In an unusual move, Ivanka Trump briefly took her father Donald's seat at a summit of world leaders on Saturday.
The US president had stepped away for a meeting with the Indonesian leader during this weekend's G20 meeting in Hamburg.
Ms Trump is an adviser to her father, but a leader's absence is usually covered by high-ranking officials.
A BBC correspondent at the summit said he could recall no similar precedent. There has been widespread criticism on social media.
Mr Trump returned a short while later to retake his seat between the British prime minister and the Chinese president.
Ms Trump did not seem to make any major contribution to the session on African migration and health during her father's absence.
A photograph of her presence was tweeted by a Russian attendee, but later deleted.
Some users highlighted that Ms Trump was unelected, or questioned her credentials - as a fashion brand owner - to sit at such a senior diplomatic meeting.
Others lampooned her appearance among the world's most powerful leaders after her claim in an interview two weeks ago that she tries to "stay out of politics".
But her brother appeared to suggest there was nothing wrong and asked the "outraged left" if they would rather he sat in instead.
Ms Trump had joined her father for an earlier G20 event on Saturday on women's entrepreneurship and finance, along with German Chancellor Angela Merkel and Christine Lagarde, the director of the International Monetary Fund.
All three women had previously appeared together on a panel during the G20 women's summit in Berlin in April.
At that appearance she defended her father as a "tremendous champion of supporting families and enabling them to thrive".
Earlier on Saturday, Mr Trump said having him for a father was the only "bad thing" in Ms Trump's life.
"I'm very proud of my daughter, Ivanka - always have been, from day one," he told world leaders at the panel on female entrepreneurs.
"If she weren't my daughter, it would be so much easier for her. Might be the only bad thing she has going, if you want to know the truth."
While her siblings, Donald Jr and Eric, took over the family business, Ms Trump put her own fashion brand assets in a trust in order to take an unpaid White House position, a move criticised as nepotism.
After a brief modelling career as a teenager, Ms Trump was given a job in her father's company.
There, she expanded the Trump hotel brand and became an executive vice-president of development, alongside her siblings.
Ms Trump is married to Jared Kushner, who also plays in influential role in her father's White House.