"Hey, so I have this crazy idea ok. What if instead of a normal house, we live inside of someone else? So what I mean is, uhh, oh! My older sister just got home so lets use her for this." Suggests Steph.
Lily is not quite sure exactly what Steph means, but happily listens to her plan anyways. "Ok, so I am going to make my older sister into our home. Her womb is where our living space will be located. And her pussy is extremely stretchy so that we can easily crawl in and out if her. Inside of her womb will be extremely large, however it will not look like it from the outside. And depending on if just one of us, both if us, or none of us are home, her body will change to appear pregnant with either none, 1, or 2 babys accordingly. So if we are both home, my sister will appear as if she is pregnant with twins."
"Um, won't it be all wet and slimy for us inside?" Asks Lily.
"It doesn't really have to be. It is really customizable. I can even give her pussy its own postal code and mailing address."
"Oh, neat. Sure, I don't mind if you are happy with it. It may be a bit weird just crawling into and out of another girl's pussy though..." worries Lily. However apparently Steph can make it so that everyone, even her sister, just thinks of it as completely normal. She even can make her sister able to keep their home clean and believes that she truely is their home primarily, and is secondarily, Steph's older sister. Also, even though she is going to be their house, she is free to move around as if she was completely unburdened by having 2 people and a full blown home inside her womb. And everything inside of her will act as if she is stationary 24/7, and always orientated correctly.
"Do you know if she is a futanari, because that may be difficult if she is?"
"Ooh, good call. I can just make her not one with this. Hmm, what animalistic features should I give her though?"