"Well, this has been fun so far," said Kate.
"The ring seems to be working pretty well," said Bobby.
"I think there's still room to be testing it," said Kate, "Plenty of kids still here at the beach."
"And suggestions of where to go next?" asked Bobby.
Kate looked around briefly before pointing and saying "There." There was a volleyball net set up and some people playing. There were plenty of other people watching, including three kids. Two of them were sisters with slightly tanned skin and brown hair, one of them look 11 years old while the other looked 9. There was also a blond boy who looked 10. They were watching the volleyball game with a look of longing.
Bobby nodded and they walked over to the kids. "Hey, you kids wanna play?" asked Bobby, putting his hand on the boy's shoulder.
"But they say we're too young to play," said the boy.
Katie put her hands on the sisters' shoulders and said, "Oh, I think they'll change their mind eventually. You'll be able to show them up in no time."
"You think so?" asked the older sister.
"Oh, I'm sure about it," said Katie before she and Bobby walked off.
"Putting it on a little thickly, weren't you?" noted Bobby.
"I'm running out of ideas for subtle approaches," said Katie.
"Well, it should at least be enough for this test," said Bobby.
The kids continued to watch the volleyball games, so enthralled that they didn't notice they were growing, not that they would have anyways. But they were also growing more excited, more energetic. By the time the older sister was 13, they couldn't stand by any longer. They walked over to one of the teams and asked if they could play. The older players were about to dismiss them, but something about the growing kids made them change their mind.
The kids seemed at a disadvantage as they most playing against college kids. But by that point, they were already in their high school years. In fact, it seemed the aging was starting to pick up speed. They were able to hit the ball back with increasing ease, most likely because they were getting taller. Their bodies were also getting a lot more fit. The boy was almost fully-grown into a handsome young man, the muscular details on his chest becoming more obvious. The age difference between the sisters blurred as they aged. They were probably twins by this point, identical twins as it was getting harder to tell them apart. Their bodies were also maturing, their breasts ripening to full size as the rest of their bodies became more curvaceous.
By the time their match ended, the three of them were indistinguishable from the other young adults. Though they did stand out from being very attractive. The young man was considered quite a hunk and the other guys envied him by having a set of hot twins on each arm. But what mattered to them right now was playing volleyball.