The Bible is relating the fact that Joseph didn't know Mary before the birth of Christ.
"And when he had taken her, he knew her not, till she had brought forth her first-born Son. He has here used the word till, not that you should suspect that afterwards he did know her, but to inform you that before the birth the Virgin was wholly untouched by man. But why then, it may be said, has he used the word, till? Because it is usual in Scripture often to do this, and to use this expression without reference to limited times. For so with respect to the ark likewise, it is said, The raven returned not till the earth was dried up.
Genesis 8:7 And yet it did not return even after that time. And when discoursing also of God, the Scripture says, From age until age You are, not as fixing limits in this case. And again when it is preaching the Gospel beforehand, and saying, In his days shall righteousness flourish, and abundance of peace, till the moon be taken away, it does not set a limit to this fair part of creation. So then here likewise, it uses the word till, to make certain what was before the birth, but as to what follows, it leaves you to make the inference. Thus, what it was necessary for you to learn of Him, this He Himself has said; that the Virgin was untouched by man until the birth; but that which both was seen to be a consequence of the former statement, and was acknowledged, this in its turn he leaves for you to perceive; namely, that not even after this, she having so become a mother, and having been counted worthy of a new sort of travail, and a child-bearing so strange, could that righteous man ever have endured to know her. For if he had known her, and had kept her in the place of a wife, how is it that our Lord
John 19:27 commits her, as unprotected, and having no one, to His disciple, and commands him to take her to his own home? [St. John Chrysostom (347-407) , On Matthew, Homely 5]
Adding other similar verses we see "behold I am with you all days, even to (
heōs, until) the consummation of the world."
Matthew 28:20. Are we to understand that once the world is consummated that Jesus is no longer with us?
“And the child grew, and was strengthened in spirit; and was in the deserts until (
heōs, until) the day of his manifestation to Israel." [
Luke 1:80]. Does the Christ lose his strength in spirit when He is revealed to Israel?
And she was a widow until (
heōs, until) fourscore and four years; who departed not from the temple, by fastings and prayers serving night and day."[
Luke 2:37] Did Anna suddenly become un-widowed after 84 years.
Did I not already address this in
post 48? All the "brothers" are accounted for by 'other mothers'.
JosephT