A Jesuit father I spoke to once on the doctrine of Hell said that we are supposed to believe in Hell, but we are nowhere told that we have to believe that there is anyone in it!
In the Gospels we are told that the only precondition for salvation is that we believe in Jesus Christ, in Him as God and in his resurrection. Quite a mouthful, I know, but we do believe in it. You are worried that your children and grandchildren are not believers, but neither you or I know that they are not going to become believers, one day, do we?
To return briefly to my Jesuit confessor: He told me that there is a line of thinking in the catholic church at present, which has neither been officially accepted or denied by the church, which means we can all believe it or not, as we want, as it isn't dogma.
It is the belief that at the actual moment of our death, we are asked, by God whether we believe in Him? If at that moment we say yes, then we are among the redeemed, irrespective of what we may have done or said during our lives.
I find this comforting and I hope you will too, with regards to family and friends who do not believe. I am sure you like I regularly pray that they may come to find belief in God - that is all we can do.
We don't know what the afterlife will be like, but if we, imperfect humans, can feel that heaven won't be very nice if the people we love are not there and are never going to be there, then surely God whose love is much greater than ours, feels the same.