Hi Devonhyia -
I'm not a tax expert, but if you're receiving rent payments on a property you own, you have to declare them as income, even if they only cover your mortgage payments. You can list the mortgage as an expense that cancels out the rental income.
You might be able to have the family member you are assisting make the mortgage payments themselves, either directly to the lender or by giving you monthly checks made out to the lender. But you should talk with an accountant or tax advisor to see just what the legal requirements and obligations would be.