Forced Desires series

It started so short and so heavy but became a whole series of shorts/novelettes.

FD 1 is between Katie and her stepbrother Carter. 

FD 2 is between Katie and her stepbrothers Carter and Brad

And then, we move to Forced Desires 3. Katie, Carter, Brad and Henry. Her stepdad. 

So yes, it's full on stepsiblings/stepdad trope and begins with NC and develops into CNC

You can find the entire series on Amazon.