You might be able to claim the person as a qualifying relative dependent and get the $500 credit for other dependents, but since they are not related to you, they cannot be your qualifying dependent for Head of Household filing status. There is a big difference in who can help you qualify for HOH filing status.
Qualifying relative
They don't have to be related to you (despite the name).
They aren't claimed as a dependent by someone else.
They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
They aren’t filing a joint return with their spouse.
When you add someone as a dependent, we'll ask a series of questions to make sure you can claim them. There may be other tax benefits you can get when you claim a dependent.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**