“To redeem them that were under the law, that we might receive the adoption of sons. And because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.” (Galatians 4:5-6)
Paul begat sons of God not sons of Paul.
“Wherefore thou art no more a servant, but a son; and if a son, then an heir of God through Christ.” (Galatians 4:7)
An heir of Paul or an heir of God?
“My little children, of whom I travail in birth again until Christ be formed in you,” (Galatians 4:19)
Paul being formed in you or Christ? I think Paul is saying that the seed hasn’t taken root (Christ be formed in you) and he is having to start from scratch because they desire to be under the law (verse 21).
Paul is clearly speaking figuratively in the sense of begetting believers. It is if I planted a plant and said I begat it because I “sowed the seed.” I didn’t sow it in the same sense that I did when I sowed the seed of my children even though in both cases I sowed seed so to speak. Perhaps I am missing something in all of this discussion.