Was Mary already espoused to Joseph when the embryonic JESUS implanted in her uterus? If so, all of her genetic reproductive future was espoused to Joseph, so to take an ovum from Mary would defraud Joseph’s espousal. That you will not admit that says a lot about how closed your mind is due to Catholiciism dogma. By being gestated in Mary’s womb, Jesus was as much heir to David’s throne as having an adopting father in Joseph made Him heir through Joseph’s line.
No, because Mary's espousal to the Holy Spirit was spiritual; her espousal to Joseph was human. Married Christians are not violating their marital vows when they become metaphorically "married" to Christ (Romans 7:1-6) and spiritually incorporated into the Bride of Christ (Ephesians 5:25-27, Revelation 19:7, 21:2f), either.