Excellent! I discovered this doujinshi after seeing the film, for those who don't know, search for "URE-028" the slut in question is "Yuko Shiraki" Thanks for sharing.
I wish there were more chapters with the other mothers, but it seems to have ended with this one. But anyway, it was pretty good.
Edit: it seems there are two prequel chapters under the title 'Tomohaha Gangu' that feature another mother, but they simply haven't been translated yet.
@orangedew The presence rule doesn't apply to a small subset of categories (ones that pose specific legal issues). Most of these categories have a 'low' version to indicate that it is there but does not pass the presence test, but incest does not.