With regard to our Lady, there are three main areas we need to look at.
First, what does the Church actually teach. Second, what does the Church allow to be taught. Lastly what is forbidden to teach.
It is not always clear to many. The Church requires us to believe that Mary is a human being, a creature of God, not a goddess or semi-divine, that she is ever-virgin, that by a special privilige she remained free from original sin, (Immaculate Conception) and that throughout her life she remained free of actual sin by her cooperation with God’s grace. We must believe that at the end of her time on earth (The Church has not officially defined that she died, or simply fell into a deep sleep before,) she was taken by God’s power body and soul into heaven. That she is in heaven with a glorified body and can interceed for us before the throne of God. These are the major points.
There are approved apparitions and visions, which are private revalation, that is the Church has found evidence that she most probably did appear and give a message to one or more people at various times and places, and that those approved visions and their messages may be disseminated by the faithful and clergy. For instance Fatima, Images of our Lady of Fatima may be utilized, Churches may be consecrated to our Lady under that title, the story of Fatima may be told and believed. It is not however de fide, no-one person who does not believe that our Lady appeared at Fatima is excluded from the Church, and no-one who holds Fatima to be true may hold that belief in Fatima is needed to enter heaven.
Then there are spurious and non-approved visions and private revalations. The Church admits that sometimes our Lady or the Saints, even our Lord sometimes appears and gives a message to individuals for the good of their own soul. If however they are to spread that message to others and proclaim that the message is for all humanity, the process is to start with ones confessor or spiritual director, who after investigation if he sees any credance in the alleged visions will discuss the matter with the local ordinary, (bishop) for approval to be disseminated. Upon investigation and approval it may be disseminated in the local diocese. If such permission is denied, it is denied, as our Lord gave authority to the Apostles, and thus to their successors the bishops in communion with the Holy Father in Rome. If the vision or message contains a message that is addressed to the entire Church, then it investigated by those appointed by the Vatican, and either approved or denied. If approved, then it may be authorized to be taught generally, but remember that it is not an endorsement by the Church that one must hold it as a requirement of faith as are the issues in the first grouping I mentioned above.
There has been a trend in the past fourty years of so to put more faith in seers or those not authorized by the Church to speak for the Church, or to counter the authority of the Church. The crisis in Faith among many since Vatican II has drawn out of the woodwork those who looking for stability rely on individual seers or mysterious priests or religious who’s canonical status is either clearly not Communion with the Holy Father, or in a grey area. It can be a grave danger to ones soul to place ones hope in these persons or groups that work on the edges or outside of Communion with the Church.
We find this in people who push Mejugore, and Bayside, which have not been authorized by the Church, and in which the supporters twist what has been said by the Church. When the local bishop would not approve Mejugore, the people turned to Rome who refused to condemn it, but simply said the Local Bishop will determine the authenticity. The local bishop still says NO, but the Franciscans at the site remain in disobedience.
As for Non-Catholic apparitions like “Our Lady of Necedah” which while condemned by the Church and approved by a group of “Old Catholic” schismatic bishops continues to proport itself as a Catholic vision and message. “our Lady” at Necedah even allegedly spoke to the seer and told her that the Schismatic Old Catholics where not to be followed “Except for the group that was at the site of the vision” Not something our Lday is likely to say. As for apparitions and miracles that allegedly happen in Eastern Orthodox Churches, and the Monophosite Coptic Churches. While approved by the bishops of those Churches for their own people, they are not approved for Catholics, until there is a proper investigation by Catholic authorities we cannot say one way or another.