Can N's mom and dad be my step-parents?

So tonight my oldest has been getting on every nerve I have, seriously.  Then at dinner we had this conversation:

Son: "Can N be my brother and you and dad be my step-mom and step-dad?"
Me: "Well if I was your step-mom, then you wouldn't really be my son." (I was also raking my brain trying to figure out how he knows about step-parents, but that's a conversation for another time)
Son: "Oh, well then N's parents can just be my step-mommy and daddy and me and N can be brothers.  They can be my step-mommy and daddy right mom?"
Me: "As much as you and N would like to be brothers, you can't be, but you're better than brothers, you're best friends, which means you two CHOSE each other to be friends, you don't get to chose who your brothers are."
Son: "Mom, sometimes the things you say make NO sense at all."
Me: "Right back at you, kid."