Reporting Rental Income

I am helping a family member do their taxes.  They own the home but live with their boyfriend, so they decided to rent it out to their family member for much less than the fair market value, the are not renting it out for profit.  I have done a bunch of research online, but continue to get conflicting information from all income is reported to does not need to be reported because it would fall under personal use.  Can anyone help?