Lisa Schneider:

One must adopt a calm composure at such times and must say that I’m going to try to help the beings who died, my loved ones and others, and be of more help to them in my next life. So that they would try to take advantage in the between-state in the after-death state in order to improve their rebirth, rather than just freak out.

What solace can Buddhism offer to survivors who have lost loved ones?

The solace to survivors who have lost someone is: Well, they lost this life, I lost my contact with them, but moaning and groaning and freaking out about it and being angry about it isn’t going to help. I should send them good prayers and good vibrations about their rebirth. If I dearly love them, I will pray to meet them again in the coming life, in wherever they are reborn, to make the world in general a better place for them, and vow to rejoin them (if it’s a soulmate sort of thing) in another life. So the consolation of Karma is not just identifying the lost beings with the embodiment of a particular life, but feeling a sense of spiritual connection to their larger continuity of life and sending good vibes toward that.

The theist says it’s God’s will and God took care of them and hopes to join them in heaven, which is also good consolation and sort of leaves it up to God. But the Karma is seeing it as a process in which you are also a responsible actor. Otherwise the vastness of the causal mixes is so huge it’s pretty incomprehensible, and no wonder some people call it God, or God’s will, or providence.

But the key thing is that Karma is not the exercise of a particular agency or divinity; it is an impersonal process of causality. — http://beliefnet.com