Melania Trump's all bark and no bite, according to a Florida school shooting survivor who says the First Lady whiffed on a chance to denounce cyberbullying from her own own family member ... Donald Trump Jr.
Lauren Hogg tells TMZ ... Melania's failed to step up after Trump Jr. hit the "like" button on a pair of tweets bashing Lauren's brother, David ... who also survived the shooting. The tweets accused David -- who's been very vocal about the need for new gun laws -- of running damage control for the FBI, and being a tool for mainstream media.
Lauren's adamant ... the First Family owes the Hogg family an apology "because (Donald Jr.) in a way kicked a wound that hasn't healed yet." She also finds Melania's silence odd, considering she tours the country talking about the need to stop bullies.
She adds, "I absolutely think it is cowardly for the first family to not condemn the accusations and trolls who are cyber bullying us.”