Whitney Houston's Brother, Sister-in-Law: We're Going to Clive Davis Grammy Party

Whitney Houston's brother and sister-in-law arrived in Los Angeles yesterday to attend Clive Davis' big pre-Grammy bash ... a bash Whitney's mom called "obscene."

Whitney's mother Cissy slammed Davis' invite, saying, "I got an invitation to the party, which is the most obscene thing. I don't know why they would want me to come to the party in which she died, you know? I guess maybe he just sent me a copy for remembrance sake."

Whitney's brother Gary -- along with his wife Pat (who was also Houston's manager) -- begged to differ and flew into LAX Saturday, telling us they were going to "support Clive."