The Nestorian heresy grew up over the controversy, Nestor believing and teaching that Jesus Christ was not merely possessed of two natures: human and divine but that Jesus Christ was actually two persons: one human and one divine.
As to Mary having been conceived without the stain and consequences of original sin on her soul (alone of all her race bjt for her Son). That suggests that she never died (the dormition or falling asleep of Mary when her time on earth was at an end) and did not suffer the pangs of childbirth. These were necessary positive consequences of being conceived without sin (original sin). I believe that these two benefits to Mary is more fully developed in the Eastern Orthodox Churches than in my own Roman Catholic Church.
I don't claim to be a Scriptural scholar and I will defer to anyone, Catholic or Orthodox who is possessed of superior learning on the matter.
God bless you and yours!