What proof, from scripture (my only valid standard), is there that Marian apparitions are valid. I do realize RCC tradition says they are, and some Pentecostals say they are not. I am not Catholic or Pentecostal.
Since all Marian apparitions occurred after the writing of scripture was over, I doubt there is any scriptural proof text proving Marian apparitions.
Our belief in them is based on the Church's pronouncement that they are authentic. The authority to make such pronouncement by the Church comes from scripture.