How do the dead people collect dua

Question

my sister told this story

A guy who fell asleep in a graveyard and in his dream he saw all the dead rise from their graves and collect these things from their graves and then went back.except for this old man who just sat on his grave when the guy asked him why he didnt collect his dua the old guy said that his son read the entire quran for him everyday so the guy asked the old man what his sons name was and he gave him the name and where he lived.so they guy went to the old guys son and told him the story and the guy said yeah its true i read the quan everyday for my father.

so the question is how do they collect the dua like the story or God just gives it to them and do they know who the dua is from?

Answer 1

 what about if the dead person passed on not speaking to one of his daughter, then would a childs dua help