Gibomai

Same story: a deceased father who's dying wish is for the two sides of his family to live with each other and love each other. He never meant for them to sleep with each other though. 

'Milfing Man' is about stepson banging stepmom while dad still in the same bed sleeping and doesnt know loL, he goes on and bangs his friends mom also, very nice. 'Stepsister' is about stepson demanding sex from his stepsister and stepmother or else he will kick them out. The mom agrees to give her daughter to him. But later on he wanted more, he want the stepmom also. Good hentai 

Same setup different story....one boy , one stepsister, one step mom....although Gibomai goes way into S/M and B/D...it's quite good. 

Another ero-anime title that's based on a Selen eroge.