The spirits in the intermediate world will see and hear us provided God allows them to. If God will. He may permit some saintly people to see and hear them and communicate with them.
After a man dies his record of deeds is not closed. If he has left behind good virtuous children or books or institutions from which people continue to benefit or if he has brought up people beneficial to humankind or contributed to their upbringing his reward will continue to increase. If by contrast what has remained of him consists in evil things then his sins will also continue to be heaped up as long as these continue to be harmful to people.
So in order to be beneficial to our beloved ones who have gone to the other world we should try to be good heirs to them by helping the poor and leading a good virtuous life and especially by spending to promote improving peoples relationship with God.