-
is this fraud actively harming someone?
-
is this fraud going to harm someone?
if the answer to both these questions is no, then just let them be. the game is rigged, playing fair when everyone else cheats is just plain stupid. its likely just one way that these folk are trying to get ahead.
if the answer to both these questions is yes: first, try to solve it like adults and not children running to mommy to tattle on "sis did xyz!! she's in such big doodoo!"
if that doesn't work, then your best bet is to first contact a trusted lawyer. then, take that lawyers advice. do not take any advice from the internet.
do not post any more information on the internet. consider this matter closed to public opinion.
good luck.