How about bunny girls? That should be nice and sexy. Nothing like that Playboy-kinda stuff, he wanted real ears and tails growing from him. So that was his descision, turning himself and his sister into rabbit lolis. Fast, jumps over buildings but still cute and sexy, and able to breed like crazy. Tens of offspring in a litter, a litter ready in a day, even more than one litter if fucked multiple times, or the litter itself getting pregnant inside their mothers.
They would grow fast in popolation, but he made the world have infinite space, so...
For himself, he put floppy ears on her new self, which shall look like a preschooler. A little girl who looked innocent yet incredibly horny and breedable like nothing else. He even multiplied ovaries and wombs, for the extra fertility, and made two vaginas, so that multiole dicks can fit inside her at once.She will never run out of eggs, that would stop the babies.
And she'd get laid constantly, not having to worry about STDs, pregnancy risks, or anything else like that ever again.
He just now noticed his hand fiddling with his crotch.
But now, the rest of her appearance. Black hair in a short cut, blue eyes, fair skin. Her vaginas will look like it should on a girl the age of five, but endure everything she will throw at them, while juice will always flow out like a stream, signaling her lust to everybody around her. Her breasts shall be enourmous, reaching her to her lap if she sits down, and constantly produce huge amounts milk from almost teat-like nipples, a few hours without milking or breastfeeding will make them gush, and her cum. It'll never hurt, though. Just pleasure.
He's gonna love it.
Beside those changes, he did tweak things here and there, removing the need for toilet breaks, increasing the sense of smell and hearing, sharpening senses beyond what humans possess naturally.
Now for her sister, he decided to maker her twelve years old with the ears sticking up, with shoulder-length black hair and red eyes and an thin body. He enhanced her reproduction, too, but much weaker than himself, Only forty in a litter, and gave her relativly smaller tits, only as big as her head, but still producing enough milk to feed her own litters.
"That should be everything," he thought to himself, as he pressed confirm.