Let me run this one by you.
A son (A) marries a woman (B) who has a son by her first marriage. (C)
So (C) now has a step father. A and B have Children (D) & (E).
C now has step father and two half siblings. B dies. A is no longer a legal step father although C decides to remain with him rather than go to his biological father.
A marries again (F) who has a child (G)
Now, A has stepchildren, his children have step siblings from new step mom, and half brother who doesn't have any connection with the new mom, his old step father or the half brother's new step brothers.
The house is full, but they all get along wonderfully.