ok while i personally will let it slide for now as we do not have too much DETAIL as to what happened EXACTLY but sora was shown to have gotten roxas memories at the end of dream drop distance so he should know marluxia even if just barely sense he left soon after roxas joined the organization. the other thing to mention is that this has not been brought up sense he got the memories sense the only game we have after dream drop distance is 0.2 and that focused on aqua so again we do not have details on what he got from roxas.
ok while i personally will let it slide for now as we do not have too much DETAIL as to what happened EXACTLY but sora was shown to have gotten roxas memories at the end of dream drop distance so he should know marluxia even if just barely sense he left soon after roxas joined the organization. the other thing to mention is that this has not been brought up sense he got the memories sense the only game we have after dream drop distance is 0.2 and that focused on aqua so again we do not have details on what he got from roxas.