After President-elect Donald J. Trump announced Monday that he would appoint his son-in-law, the real estate investor Jared Kushner, as a senior White House adviser, lawyers for Mr. Kushner said he would sell many of his assets to avoid myriad potential conflicts of interest.

But because he plans to sell to his brother or to a family trust controlled by his mother, some ethics lawyers interviewed questioned how meaningful the divestiture would be.

Jamie S. Gorelick, a lawyer who is advising Mr. Kushner on how to deal with the ethical issues he will have to navigate while advising Mr. Trump on topics that could affect his bottom line, said Mr. Kushner would sell his interest in about 35 investments, including his family’s flagship office tower on Fifth Avenue in Midtown Manhattan. He also plans to restructure his role in his remaining holdings so he will not be involved in managing them, Ms. Gorelick said.

In addition, she said, he will sell his common stocks; resign as chief executive of Kushner Companies, his family business; and sell The New York Observer. He will also recuse himself from decisions that could affect his remaining holdings, as well as those of his wife, Ivanka Trump. “He will be treated as any other person entering public service,” said Ms. Gorelick, a partner at WilmerHale and a deputy attorney general under President Bill Clinton.