Did St. Joseph have a first wife named Melcha?
The short answer
The story that Joseph married a Melcha and had six children comes from apocryphal writings, which have no authority, as the Catholic Encyclopedia notes.
The tale that Joseph married a woman named Melcha and had six children comes from the apocrypha and carries no authority.
The Catholic Encyclopedia's article on St. Joseph recounts these stories while calling them unreliable: married at forty to a woman called Melcha, Escha or Salome, he lived with her 49 years and had two daughters and four sons, the youngest being James, "the Lord's brother." After her death, at ninety, he was chosen by a miracle to espouse Mary, then 12 to 14, two years before the Annunciation.
St. Jerome called these "dreams." They have no authority, though they inspired artists (such as Raphael's Espousals of the Virgin), gained popularity over the centuries, and were used by some writers to explain the Gospels' "brothers of the Lord." They are also the source of the popular belief, contrary to probability and to the tradition of old works of art, that Joseph was an old man when he married Mary.