I assume closely related hominids which are now extinct. Neanderthal DNA is present in current human strains, which means they didn’t even speciate (though potentially successful gestation was rarer).
Why am I writing like an alien nerd observing humans?
I’m hiding a homeless person in my home, which is risking eviction to keep someone off the streets. Here, most tenancies don’t allow you to “sublet”, the landlord legally gets the final say about who lives in their property.