In that role, the trio will have input when it comes to the people Trump picks for key administration posts.
Watchdogs who were critical of Trump's "blind trust" in the first place say this proves that the lines between President Trump and his money will be too fuzzy under this setup.
"The fact that they have been included as part of the transition team just shows how inappropriate their role in bridging the gap between him as a businessman and politician is," said Meredith McGehee, a strategic adviser at the Campaign Legal Center. "It’s a clear demonstration that there is no firewall between the two."
McGehee and others have also cast doubt on the idea that the so-called "blind trust" is actually blind at all. She calls it a "one-eye-closed-and-one-eye-open trust."
In addition to blurring the line between Trump's presidency and his money, skeptics note that his children will now also have control over the people who will be put in charge of regulatory decisions that could affect his multi-billion-dollar fortune.
Kenneth Gross, a political law expert at Skadden, Arps, Slate, Meagher and Flom, said it would be okay for Trump to involve his kids in the transition, but their dual roles are problematic.
What President-elect Donald Trump did on his trip to Washington
"If the children run the so-called blind trust and also serve in some governmental capacity, formally or informally, this would further exacerbate potential conflicts and ethical issues caused by not separating his business holdings from his governmental functions," Gross said.
Added Karen Hobart Flynn, president of Common Cause: "Having your children run your business is not a blind trust no matter what his attorneys choose to call it. And having those same children involved in the transition only compounds the conflict."
Reporters also reacted Friday afternoon with incredulity at the inclusion of the Trump kids on the transition team.
The transfer of the Trump Organization into his childrens' hands was reportedly being formalized Friday.
Cohen, who is a lawyer for both Trump and the Trump Organization, detailed the "blind trust" arrangement -- which had previously been floated during the campaign -- Thursday in an interview with CNN. But "blind trusts" are generally considered to be situations in which the assets are controlled by independent parties who aren't in touch with the owner.
Questions about how truly "blind" they are come up regularly in politics. Back in 2012, Mitt Romney was criticized for not having a true blind trust, given it was run by his old colleagues at Bain Capital, and Romney could easily see what Bain was up to.
Nor is this the first time that potential financial conflicts of interest involving children have come up in this campaign. Watchdogs previously pressed Hillary Clinton not to leave daughter Chelsea Clinton in charge of the Clinton Foundation if she had been elected president.
Cohen said on Thursday that Trump has no interest in growing his fortune as president. (It would be impossible to know if he did because Trump has never released his taxes.) But Cohen acknowledged the set-up won't please everyone.
"Will we be able to appease everybody? The answer is no. No matter what the man does, he can’t appease everybody,” Cohen said. “But everything will be done legally. He’s not interested in the company anymore. He said it [Wednesday] in front of a whole group of people. He’s interested in fixing America."