Trying to help my sick step sister by cumming into her mouth

Stepbrother is very caring. He wants to help his sick step-sister. She has pain in her throat. Her stepbrother cum inside her mouth & she likes it. The next day her stepbrother again comes to see if she is OK & he tells his step-sister that maybe they can fuck cause they are not related to blood. And that will help her to recover. Step sister loves his dick & fuck in Doggystyle.