My adhd muse has me developing a plot with the step mother and stepson meeting before the wedding without knowing who they are and relationship continues. I text searched the story list and nothing jumped out as having a similar setup. I just want to see what others have done with the circumstances.
I seem to recall reading a couple of those, yet I doubt I saved those, so can't recall the titles. Try searching for "stepmother" and "stepson". You may get a few false positives, yet it makes it easier to limit the search too (ex: if the stepmother and stepson aren't the one's engaging in sex with the protagonist).
Plus, those were likely short stories rather than an extended series, which typically age out sooner as well.