Well, that served for being as good of a test run as any. So now with confidence in the powers of the device Jeff was getting a lot of ideas. However one thing was bugging him a bit. His sister had become a chair, and only he knew about it. If he ever forgot, she would literally be trapped there forever. So opening up her profile, he made just a few edits and set up a failsafe for her.
Basically, only he would be able to see her as herself, and not as a chair. He also made it so that they could speak in his head if he ever sat on her. Additionally he made her indistructable and completely fire and water proof. He also gave her the power to freely swap back and forth between the two forms. Lastly he made it so that if he ever forgot about her, or she was thrown away, or for some reason she no longer was still with them (like theft, property seizure, or just sold), she would return back to normal automatically.
Now that this was done, he went to see how things were. Peeking at his chair sister, he could see her completely naked body being sat on by their mother. Interestingly, his sister wasn't completely immobile, as her head and various area's of her body were moving slightly here and there. She had a huge grin on her face and would have been making various happy noises if she could still oroduce sound. Clearly she was enjoying herself, completely unaware that her real form was being watched by her brother. Jeff kinda found it weird though how her arms had lengthened significantly in order to form the back legs, and her breasts were what made the arm rests. She was standing on tip toe as well as just using her finger tips to hold herself up.
Jeffs mom got up and went into the living room to sit on the couch. So Jeff quickly sat down on his sister and explained everything to her. She complained about being able to freely swap as it took away from the excitement of being stuck as just a chair, but she understood why he did it too, so she didn't push to undo it too much. She knew it was for her own good anyways and would ease most of the burden she had kinda just forced onto him. So she let it stay too, much to Jeff's relief. "By the way, out of all the chairs, did you have to break the one I use?"
"Obviously, you would never use me if I didn't. I want that ass squished on top of my lap and your hands on my, um, arm rests..." she was about to say breasts, but remembered that Jeff could not see her body like she could (or so she thought) and switched to arm rests to not deter him from using her even further.
"Oh, one other thing which I forgot to mention sis. I made it so that only I can see your real body besides you as well. Just incase all else fails, I can't forget you if I can see you. Which means that I know you are currently naked, and that your arm rests are your tits, you pervert".
Jeff stood up, getting off of his sister's lap. While doing so, he intentionally pushing the bulk of his weight into her tits in order to lift himself up. And since he still had direct contact with her, he could hear her shrieking in extacy. It would seem that his sister's masochism would be reach a new high today.
The moment his fingers left her breasts, he couldn't hear her anymore, since he no longer had any point of direct contact. As he turned to head back to his room, his sister's voice came shouting from behind, which startled him. "Hey, make me into your personal chair! From now on, whenever you sit, I want to be underneath you holding you up."
Jeff was stunned at what his sister just said. She didn't just want to be an inanimate object, she wanted to be his exclusive inanimate object. Which now that he thought about it, wasn't so inanimate to him anymore. He made this conclusion based on the fact that she could revert just parts of her body it seemed, as only her head was moving freely and looked normal, while the rest of her was still "chair shaped". Then his mom even chimed in from out of nowhere. "Jeff, let Emily-chair be your personal seat. She IS your sister-chair afterall. We are a family, which means we support each other with our best. It just happens to be rather literal for her."
"Even mom is taking her side in this?" Thought Jeff, surprised that she even recognized Emily as being her daughter, but also still just a chair. The reality altering setting must be adaptive, and since her head is back to normal, she is now seen as both a chair and my sister, but mostly just a chair. "Fine whatever, but just keep the shrieking to a minimum. okay?" Said Jeff loudly as he grabbed his sister's back rest and lifted her up. Luckily, she now weighed as much as any of the other chairs, so he could do this with relative ease. "Now Jeff, you know she feels extreme amounts of pleasure when she is used. You are not, nor have ever been a women nor a chair, so you likely don't know just how hard it can be for us to keep silent when experiencing these extreme levels of pleasure." Chastised his mother. "You should know that I use to scream my lungs out when your father used to sit in me while we were dating. And like any other piece of furniture, as time goes on, we get used more and more, so the pleasure drops down to a more manageable level as we age. But that is usually at least after we turn 30 or so. Your sister should be nearly losing her mind. Not that she will, but it just feels that good to be used, especially if it is by someone we love. You guys are step siblings, so there is no significant issue with her loving you romanticly."
Ok, there was a lot of things wrong with what his mother just said. He looked over to correct her when he finally noticed it. His mother's head was sticking out of the top of the leather recliner. His mother and sister had become some kind of chair people, and must have married into his family, bringing Emily along with her. Reality altering was really scary at how much gets changed to set the "new normal". The world was becomming really weird now, and Jeff felt he had to put a stop to it before things got too far out of hand. At minimum, he had to restrict the RA (reality altering) system to just make his sister seem normal, not change the entire world to make his sister normal.
Sighing, Jeff carried Emily up the stairs to his room, where he set aside his normal chair and placed her in it's spot, much to her delight. However he placed one of his blankets from his bed over her so that he didn't make direct contact with her in order to not hear her shrieking. He had noticed a clear plastic cover slip was on their mother's chair body, and that was what gave him the idea to try his blanket. To his relief, that did the trick for the most part. He could still hear her, but it was like she was on the lowest volume setting possible, as she was just bairly audible now.
He opened up Emily's profile for a third and hopefully last time and began making the new changes. He did consider just returning everything back to normal, but he decided to not, for now at least. His sister was now extremely happy. Happier than she has ever been to his knowledge. If keeping that meant he had to sit on her for a while longer, then he could live with it. Even if it did mean that his sister now wanted their relationship status to switch from siblings to dating. He also made the screaming and shrieking stop completely. That shit had to go, so he lowered the pleasure to a more reasonable, but still significant amount. On an impulse, he also made her able to take the shape of any kind of chair he wanted, since the dining room chair was no where near as comfortable as his computer chair was, even if it was made out of his now official step sister's body and not solid wood.
Finishing the edits, he pressed enter and got up to remove the blanket. When he did, he was met with a quite disappointed, and pouting face of Emily. "You turned it down." She pouted.
"I had to or you wouldn't stop shrieking." "But it doesn't feel as good now!" She continued to whine. However you just ignored her and sat back down, causing her pout to break into a smile again as she started curving her "arm rests" more and more around your body attempting to hug you with her breasts since her arms were now her back chair legs. Interestingly enough, the sight of her tits streatching out around you not only didn't bother you, but sorta turned you on as well, which Emily took notice of almost immediately.
She quickly changed her shape slightly to a 3 legged chair, freeing up a hand which she used to rip your pants off with before returning to her "normal" 4 legged shape. While you were without pants, she used her breasts to begin massaging Jeff's dick, activating a set of vibrators within them as she changed herself partially into a vibrating chair while softening her arm rest ends to feel just like her normal breasts. Jeff hated how much he was enjoying the service. Emily was really good at doing this it seemed as he came, coating her breasts with cum, which Emily let just remain on them as she brought them up to her mouth one at a time to lick them clean and swallow all of the cum they had on them. While she was doing this, Jeff was busy thinking of more ways to use the device.