Does Melissa inhale her sister's scent?

Yes, and more

Melissa doesn't hesitate a second longer, she takes a strong smell of her sisters finger, and Angela smiles wickedly.

"What do you want, Melissa?" Angela asks.

"I want to taste your cum, I want to become a Succubus!" Melissa says, and before Angela can even react, she reaches over and starts to finger-fuck her sister.

You watch in horror as Angela presses her pussy up against Melissa's mouth, and she happily licks and fingers it, you knew it was too late for her now. But at the same time, you're getting very horny, your cock now at its full length as Melissa plunges her tongue deep into her sister's Pussy.

Over the next couple of hours, they pleased each other as often as they could, nearing the 2 hour mark, you start to see their skin turning the reddish hue of a Succubus. Their horns and wings grow out, and their breasts inflate as their long tails grow, and their hair turns pitch black. The two newly born Succubae now turn their attention to you, smiling with glittering fangs.

"I ssshould thank you," Angela says, her serpentine tongue flicking out. "Sssince I had to wait ssso long, Massster Sssatan has given me more power than I'd ever imagine, I can change the form of my conquessstsss in anyway I want, but what to do with you?"