An alternative proposal from Tim Yearsley
“This passage is clearly a tipping point in the relationship between Jesus, Mary and Joseph. The passage commences referring to Mary and Joseph as ‘his parents’, traversing through to ‘Joseph and his mother’ via “my Father’s business’ to the point where ‘his mother kept these sayings in her heart”. Given the bookends in vv40 and 52 I suggest there may be a structure highlighting the tipping point in Jesus’ advancing maturity and relationship with his Father, now apparent to those who were astonished at his understanding and answers such that he was increased in favour with God and man.”
A Child’s (Jesus) growth
40 And the child grew, and waxed strong in spirit, filled with wisdom: and the grace of God was upon him.
B Travel to Jerusalem from Nazareth with parents
41 Now his parents went to Jerusalem every year at the feast of the passover. 42 And when he was twelve years old, they went up to Jerusalem after the custom of the feast.
C Joseph and mother didn’t know Jesus stayed behind
43 And when they had fulfilled the days, as they returned, the child Jesus tarried behind in Jerusalem; and Joseph and his mother knew not of it.
D Joseph & Mary sought Jesus amongst their kin
44 But they, supposing him to have been in the company, went a day’s journey; and theysought him among their kinsfolk and acquaintance. 45 And when they found him not, they turned back again to Jerusalem, seeking him.
E Astonishment at Jesus understanding
46 And it came to pass, that after three days they found him in the temple, sitting in the midst of the doctors, both hearing them, and asking them questions. 47 And all that heard him were astonished at his understanding and answers.
D’ But Jesus was found about his Father’s business
48 And when they saw him, they were amazed: and his mother said unto him, Son, why hast thou thus dealt with us? behold, thy father and I have sought thee sorrowing. 49 And he said unto them, How is it that ye sought me? wist ye not that I must be about my Father’s business?
C’ Joseph & Mary didn’t understand
50 And they understood not the saying which he spake unto them.
B’ Travel from Jerusalem to Nazareth
51 And he went down with them, and came to Nazareth, and was subject unto them: but his mother kept all these sayings in her heart.
A’
Jesus advancing maturity
52 And Jesus increased in wisdom and stature, and in favour with God and man.
I agree, thanks for that.