Praise be to Allaah.
There is no saheeh evidence (daleel) to indicate that this practice is prescribed in shareeah. Therefore it is an act of bidah (innovation) which we should avoid, warn others against and not take part in. We should adhere to the sunnah, which contains sufficient alternatives to all the innovated practices. The hadeeth Recite Yaa-Seen for your dead is a daeef (weak) hadeeth. See Question #734. And Allaah is the Source of strength..