If he has a son or a daughter who is a business person, it should be assumed that when the President's offspring travels with the President nationally or internationally, that son or daughter will likely be on the trip in order to make a buck by taking advantage of daddy's position, power, and prestige.
What can and should be done about this? Maybe a new "LEAVE YOUR CHILD AT HOME" Presidential Travel Policy should be instituted. Or perhaps the President or someone high up in the President's White House staff should publicly announce, at the start of each new Administration, that neither the President's siblings nor the President's children nor any of the President's other relatives, whether by birth or marriage, will engage in any business activities or take any business meetings -- either in-person or electronically -- while traveling with the President or visiting or being visited by the President, or in the company of the President.
Separate the children's private business ventures from the father's very public duties and responsibilities, and MAKE THAT SEPARATION IRON-CLAD!