OK, then what is your explanation of the mechanics of the starting point of the person Mary gave birth to? Did God just zap a baby in there or what? If He did, then how were the lineage requirements met? Would the title "Son of David" really fit through adoption by Joseph? That sounds pretty forced to me, and completely unnecessary.
To speak of any kind of "conception" as we know it is plain fantasy.
The Bible says "conceive". That usually involves "conception". What do you think it means?
Luke 1:31 : And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS. (KJV)
The "mechanics" is a unique term called Incarnation, which can be awkwardly translated as "enflesh." As far as I know, it is uniquely used only for Christ. No other conception is termed "incarnation."
Incarnation is a mystery (miracle) of God which, by definition, remains incomprehensible, yet you seek an "explanation."
The Bible says "conceive". That usually involves "conception". What do you think it means?
I think the term conception is used as "having been left with a child" and not in the modern sense.
Clearly, the Christian undertsanidng of the conception in this case is that God the Word took on the flesh (human nature) of Mary.