You stop her.

"You are way too good at that, but I want to only cum inside you." You say

"Of course! Can't waste sperm like that! Come over here, so you can fuck me." Neon says.

"Before we start, let me do something." You bring out your phone and press the virgin button.

"What the fuck is that? Did you make something grow inside me?!"

"I made you a virgin again. I hope that isn't an issue?"

Neon thinks for a second, "No, I guess not. Being deflowered then impregnated? Why did I not think about that before! This is going to be great!"

Amelia walks over to the bed in the corner and lays down, "Come over here, Kitty. I will need to feel good as well while my brother rails you."

"Wait... Bro-?" Neon tries to say.

"Don't think about it." You say.

"Whatever, I don't judge those things." Neon walks over to the bed and puts her face into Amelia's pussy.

"oh god! Have you practiced this before?"

Muffled, Neon seems to say something like, "My friend let me do this to her all the time!"

You get behind and start playing with her. You realize she is already dripping wet, so you start rubbing the head of your dick on her.

Neon stops licking, "Don't tease me. I need it inside me, please!"

Obliging, you thrust in, breaking her hymen in one movement.

"ohhhhH!" is the only sound that comes out from Neon. Amelia shoves Neon's face back into her pussy, and holds the katt there. You start to thrust slowly, and as you do, Neon's tail wags. You grab her tail, which makes her yelp first. She cums after a few seconds, as does Amelia.

"There is something I want to try. Let me do something." Amelia grabs her phone from beside the bed, you have no clue when it got there, and she hits a button. Neon immediately gags and pulls back as the new dick is shown.

"How did you-?" You begin to say.

"I can't impregnate girls with it, but it seems to be a gift from the goddess that gave you your powers. It lets me do whatever I can to help you breed."

"Goddess?" Neon asks.

"Don't worry. What did you want to try?"

"Flip her around, and hold her up. Stay in her pussy."

You do as she says, and Neon is now facing you. Amelia stands up and puts some lube, something that might have been left by Ozpin, on her dick before shoving it into Neon's ass. Neon moans loudly as she does. "No one has ever put it up there before! I love it!" You both begin to roughly fuck Neon in both holes. She cums several times as you both use her as a toy. You even switch holes so that you can try it for a bit. You ask Amelia to step back a bit, which she does. You let Neon lean forwards and move to her pussy. Amelia gives you a look and nods as she places her dick into the faunus's mouth. You both start fucking her in rhythm, and you can hear her moans and screams as she deepthroats your sister. Eventually, you come close. "I'm about to cum!", "Me too!". Neon cums as well as Amelia fills her mouth, and you impregnate her. You all fall to the bed afterward, and Amelia's dick shrinks until it disappears.

That one was different for me to write. Hopefully, that is not too bad.