Russian lobbyist also attended Trump Jr.'s meeting with Russian lawyer

According to The New York Times, a former Soviet counter-intelligence agent who currently is a lobbyist for the Kremlin in Washington, was also present during the meeting between Donald Trump Jr., the Russian lawyer Natalia Vaselnitskaya, Jared Kushner and Paul Manafort.

Donald Trump Jr. had previously not disclosed this fact about the meeting.

From the NYT article:

The presence of the Russian-American lobbyist, Rinat Akhmetshin, adds another twist to the evolving story about the meeting, which Donald Trump Jr. set up after learning that the lawyer had damaging information about Hillary Clinton. Donald Trump Jr. also invited Jared Kushner, the president’s son-in-law and a campaign adviser, as well as Paul J. Manafort, who at the time was the campaign chairman.

Not exactly a small item to forget. Sounds more like an item that was conveniently "forgotten" by the Trump campaign.