There is so much in our lives that my father and Mary's parents have missed out on. Its times like those when we realize how empty a room crammed with people can feel. There were three empty seats at our wedding. We set up a small table off to the side of the altar that pictures our deceased parents. The officiant said the traditional Jewish mourner's prayer as I placed two roses in front of her parent's picture and she placed a single rose in front on my father's picture. It was all we could do not to cry.
There's a hymn about heaven that says, "Lets see Jesus. Then let's go find our dad and mother." It will be the day with no more tears because those things will have passed away.