She accepts it, acquires it to keep it from escaping, and carries it in in case Andi wants it too.
"Hi, guys. It turns out Andi is some kind of morphing prodigy. She can include clothes, and control order of operations, and she's six times faster than me at the butterfly. She also figured out how to stop in the middle, but I can do that too, now."
"I can't do just any clothes, they have to be pretty snug," says Andi, who is in fact wearing a tube top and leggings. "But they just sort of come along, if I want them to - not when I'm turning into Bella, though, then I want them to stay where they are."
"Fascinating," says Ethan. "Could you attach one outfit to each shape, I wonder?"
"She's not going to do it in front of you. Andi, you think you can take notes by yourself while I watch these guys?"
She heads for the basement, while her sister goes up the stairs.
"So," says Ethan, "are we going to stick to some kind of experimental structure or should I just keep breaking things until something sticks?"
"No fatal wounds, nothing we cannot possibly explain as 'Trouble fell off the roof' or something if he winds up unable to morph like Elfangor - you're morphing Robin, Trouble, not one of the Andalites?"
"Yeah," he says, "otherwise I'd bust my clothes - I guess if I figure out Andi's trick that won't be as big of a problem, but one thing at a time, and this thing's more fun."