I suspect, most strongly, that they are a narrowly selected student "community" that is highly, tightly, obediently, and aggressively organized and funded by adults, whose names everyone would recognize.
They were also well trained for this well in advance.
It’s not a conspiracy theory to say this. They’ve trained thousands of kids across the country to become future liberal parrot talking heads. Parkland was one of their nests. CNN has some sort of program for young voices, for example—which just happened to involve two of these Parkland anti-gun kids.