It's not a big deal. If you have your citizeship in Nepal, ask your brother to make a "Relation verification certificate" including you, yr parents and bro/sis. KMC would ask verifying documents that's for sure. There is nothing strict in putting the relatives in this relationship certificate. I have seen some certificates even with cousin. And regarding visa it's all your luck and mood of  those *************  counselors. Sometimes they dont bother to issue visa for far relatives (goru becheko saaino) but reject the proper candidate.