According to the IRS, renting to relatives may be considered personal use even if they're paying you rent, unless the family member uses the dwelling unit as his or her main home and pays rent equivalent to the fair rental value.
As you cited in your question, this matter is covered in IRS Publication 527. The key takeaway from this Pub is that they are paying below fair marker value and therefore any income reported would be exhausted by your expenses resulting in a loss which in your case would not be deductible. So in essence it is a "wash."
You may find the following link helpful:
https://www.irs.gov/faqs/sale-or-trade-of-business-depreciation-rentals/personal-use-of-business-pro...
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