Jesus was fully human and fully God....the fully human was formed in the womb when the Word became flesh.
The Bible says to be "fully God" is to be Spirit...
John 4:24... God is a Spirit: and they that worship him must worship him in spirit and in truth.
The Bible says to be "fully human" is to have a human spirit, a human soul, and a human body.
1 Thessalonians 5:23... And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.
So how would YOU describe the connection between the Word (fully God nature) and the fully human nature of Jesus?
In other words, is it "the Word added the fully human nature of Jesus to his divine nature so now He has two natures" or something else?
Here is how I personally describe the connection between the Word and Jesus...
For this creation, YHWH God (the only one who transcends all creations) determined to create a universe with a kingdom of redeemed humans (living souls) for his glory where he would reign as a living soul himself. The Scriptures describe how God would accomplish his plan. In an instant, transcendent God (called God the Father) created the supernatural and space-time of this universe and also became immanent as a spirit (called the Spirit of God) and in the form of a living soul (called the Word of God) with a glorious body. God the Father then created all things within the universe by the power of the Spirit of God commanded by the Word of God. But whereas God created a human spirit and soul for each of us, God himself as the Word became the human spirit and soul of Jesus. At his conception, Jesus' glorious body was changed to a mortal body to be made like us so he could make reconciliation for our sins. At his resurrection, Jesus' mortal body was changed back to a glorious body and he will also give each of his elect a glorious body when he returns to reign in his kingdom forever.