Yes...I don’t know the name of the Bill nor the E#, but igt was put in place to stop any other president to do what JFK did with Bobby.
As far as I can find out (thank you internet!) the Federal Anti-Nepotism Statute is indeed ‘5 U.S. Code § 3110 - Employment of relatives; restrictions’.
From that it looks like Trump could - could! - put his entire family in the Cabinet. He just couldn’t put them on public payroll.