<p>Oh. The Battle of the Department of Mysteries.</p><p>Well that be Neville, Ginny, Harry, Ron, Hermione and Luna.</p><p>
</p><p>Harry and Luna's reasons are explained.</p><p>Neville witnessed the death of his
grandfather which also allowed him to see Thestrals.</p><p>
</p><p>As for the rest... well the only logical explanation I can go for is that during the world cup whatever happened to Fred, george and Ginny was never explained. For all we know during the chaos they may have saw a Death Eater murder a complete stranger or something.</p><p>But on the likeliness of that not being the case, Neville, Harry and Luna could of simply helped Ginny, Ron and Hermione get on their thestrals and lead them as a herd.</p>