What was the relationship between David and Joseph?
Joseph, the husband of Mary, was of the family of David. That is why he went to be enrolled in Bethlehem, the city of David. Matthew 1:20; Luke 2:4
What the Bible says
Matthew 1:20
But while he thought on these things, behold the angel of the Lord appeared to him in his sleep, saying: Joseph, son of David, fear not to take unto thee Mary thy wife, for that which is conceived in her, is of the Holy Ghost.
Luke 2:4
And Joseph also went up from Galilee, out of the city of Nazareth into Judea, to the city of David, which is called Bethlehem: because he was of the house and family of David,
Douay-Rheims Bible (Challoner revision), public domain.
Did you know?
Luke says that the angel Gabriel was sent to Mary, who was betrothed to Joseph, of the house of David. Luke 1:27