Jason thought it over. The katana had a number of different features, but it occurred to him that he could combine them.
It was a simple idea: First of all, cut parts off of someone using duplication mode. Then detach someone's existing part, replace it with one of the duplicates, and stab the detached part with the vanishing mode so that there isn't an extra part left behind. The effect of the whole procedure was that you could replace someone's body part with a copy of someone else's body part.
He made cuts dividing the 14 year old into three parts, then the 9 year old. One by one, he replaced each of the 9 year old's three parts with copies of the 14 year old's three parts. The end result was that the all of the 9 year old had been replaced--she was now a twin of the 14 year old.
Too late, Jason realized he hadn't considered some things. For instance, if you erase a part containing someone's head and replace it with a copy of someone else's head, does that just keep them the same person with a different looking head, or does it actually kill them and create a different person with a different brain? It was magic--it could work in a lot of ways. But it was too late now.
He deactivated the katana. The mother and the 14 year olds just started to walk off. It seemed that in the altered reality, they were identical. so they must have agreed where to go. They had never argued over where to go, never stopped. He had successfully used the katana to end the argument. And now he knew that by combining duplication , cutting, and vanishing, he could replace parts with a copy of someone else's parts. That could be used for a lot more than just those two girls. Jason considered the possibilities....