Coming down from the high of being with your mother, you can't help but notice your sisters comparatively normal proportions. Even her pornstar body, the very same you used to shamefully jerk off thinking about, seemed boring compared to what you'd just experienced. You can't help it. A devious grin spreads across your face as you look down at the remote. You quickly hit the pause button, which does exactly as you would expect, freezing time for everyone except you. You silently vow to not give into temptation until your sisters body is fully mutated.
You decide to start small. You make Jenny a foot and a half taller. She sprouts up to an impressive 7.4 feet tall with broader shoulders, longer legs, and even more muscle than she already had. She looked more like a barbarian warlord than any average athlete. Sadly, her assets hadn't grown to match. A problem you easily rectify, as you aim the remote at her chest and watch her boobs inflate like water balloons full of jello.
You keep the invisible radio waves of the magic remote locked on your sisters rack longer than you probably should have. Mostly you just wanted to see how big they'd get before breaching the containment of Jenny's sports bra. It took much longer than expected, and by the time her massive mounds freed themselves they had transformed into truly gravity defying moons, each twice as large as her head and together wider than her shoulders. As they break free they wiggle like massive waterbeds, clearly packed to bursting with rich creamy sister milk. Her nipples had grown, too. Each puffy areola supported a phalic 4 inch nipple as thick as a cock and leaking. It was hard not to pounce on them right now, but you had already come so far. You have to finish the mission.
Deciding retroactively that your sister inherited a few more of your moms endowments, Jenny's legs part as a massive cock springs out from between them. It's only slightly smaller than your mom's, but still easily big enough to give herself an effortless titjob when hard. Aiming your remote slightly lower, you enhance her balls next. The readout on the remote keeps you informed on just how much her nuts can output as they grow. 1 litter, 2, a gallon... eventually you stop it at 2 and a half gallons of total storage, giving your sister 2 massive melon sized spunk factories full of milkshake thick hyper fertile baby batter. When these badboys drop their payload it's guaranteed triplets. You almost pass out thinking about giving yourself a womb and experiencing it yourself, but once again you hold it together. Only one more change before you can unpause time.
Aiming the remote like a phaser, you make your final alteration. Your sisters washboard abs quickly disappear under the strain of new life artificially placed inside her. Her hips widen and a thin layer of fat covers most of her form. The children inside of your sisters womb are quickly aged up to 18, and bestowed with an intelligence to match. You're a freak after all, not a monster. Just for the shits and giggles, you also make the kids half from you and half from your mom, making sure to remove any incest caused defects from their biology on the surprisingly intuitive digital display of the remote.
Finally looking up to admire your work, it's hard to believe this person was ever once your average looking sister. Every single one of her assets are hyper and engorged. Her stomach presses out the furthest, as it contains 4 other full sized adults within its walls. Her breasts rest on either side, looking ready to spray milk like twin super soakers as soon as time is unpaused. Her massive cock and balls look ready to do the same, cum already forcing its way towards the tip and sure to spray like a fire hydrant the second that reality resumes. Her baby fat is primarily concentrated on her ass, which you can't exactly get a good look at while she's sitting, but you can tell it'll be just as heavenly as your mother's.
The choice paralysis of what to do with this brand new Goddess of fertility in front of you is like a thousand pounds on your back. Eventually you narrow it down to 3 options.