There has to have a rooj Xim aka rooj plaub rooj lus. But all can be taken care of by the Kavxwm. Xivxaiv is not required.
When my father passed away, we dont even have Xivxaiv, per his final wish. During his last few weeks, probably he knew he's going to go, he said, "Kuv tej lus nyiaj lus kub, tej koob tej hmoo ces twb muaj tab rau cov uas hlub kuv, nrog kuv nyob. Kev ua nom ua tswv ces leejtwg hlub kuv ces tau zoo, kev ua neej kuv twb qhia tag rau nej. Yog tias kuv tus mob tsis tso kuv tseg, es kuv tau mus lawm tsis thas hais tej lus uas tsis yog kuv lus."