Jesus' Lineage

Today I was reading Luke 1 in my daily reading. Luke records that Elizabeth was of the daughters of Aaron (Lk.1:5). Later Luke records that Mary is a relative of Elizabeth's (Lk.1:36). That seems to me that Luke is either hinting or stating that Mary is also of the daughters of Aaron or at least connected in some way. Leon Morris in his commentary on Luke (Tyndale NT) says that Mary must have been of Levi and of Judah otherwise Jesus could not have been a son of David and thus a legitimate heir to David's throne as the messiah. Yet, both Luke and Matthew show that Joseph definitely is a descendant of David's (Luke 1:27; Mt.1:16) but don't really state anything about Mary other than she is a relative of Elizabeth's. Is it possible that Jesus' blood lineage is of the tribe of Levi through Mary and his adopted lineage through Joseph is of the tribe of Judah and thus David? Has anyone read anything on this subject?

I had been wondering if this was what Zechariah meant in 6:13 when he says that the messiah will be a priest on his throne combing the offices of priest and king. But I realize that Jesus is not a priest after the order of Levi but of Melchizedek (Heb.6:20). I'm now wondering if perhaps Jesus came as a legitimate heir to Aaron as high priest but instead becomes a different priest altogether and thus effectively ending the Levitical priesthood by accepting an appointment to another priesthood. Again has anyone read anything about this or am I just all wet in regards to this subject?