An honest question here because I am honestly confused by your post.
Where does Scripture say that Mary is of the house of David?
Where is her lineage cataloged?
Neither Matthew, who lists the lineage to Jesus, nor Luke who lists it from Jesus, list Mary. Rather, both make note of Joseph’s connection.
In the story of the dream of Joseph, it specifically says that Joseph is the descendent of David and nowhere that I can find does it say that Mary is.
If I am missing something, please direct me to it.
Luke 3:23-38. Notice verse 31 in particular.
http://www.biblegateway.com/passage/?search=Luke+3&version=ESV
It differs from the genealogy in Matthew in Matthew 1:1-16
http://www.biblegateway.com/passage/?search=Matthew+1&version=ESV
Notice in Luke 3 the lineage goes back to Nathan. Mary’s lineage goes back to David’s son Nathan.
Luke 3:31 Which was the son of Melea, which was the son of Menan, which was the son of Mattatha, which was the son of Nathan, which was the son of David,
Then notice in Matthew 1 the lineage goes back to David’s son Solomon.
:6 And Jesse begat David the king; and David the king begat Solomon of her that had been the wife of Urias;
Both Mary and Joseph go back to David each through a different son of David.