If the stepdaughter is already interested in these pictures and videos, then her pussy is ready to be used for its intended purpose. And the stepfather has more right to her than anyone else. He catches a glimpse of her getting a high from his cock, sucking vigorously and greedily. Twisting her around and putting her upright - the man drives the bolt all the way up to her balls. Such a stepdaughter in the house is a godsend. Let her work hard to strengthen the family.
I can see it's not the first time they've had sex together. It's so convenient - you don't have to take anyone off, there's always a shower and a bed nearby. Of course, her brother's dick is great, so any sister would fall for one and suck it at the first opportunity. Well, it seems to me, he doesn't mind having fun with his sister with it either - his own soulmate won't betray him or make him marry him. It was so cute when her brother came inside her - it just cheered them up. )
It's just that...