Did Mary have other children?

Answering purely from Scripture:

One answer is taken from : Mary: Perpetual Virgin? 6 Biblical Arguments | Dave Armstrong, and the rest my own.

Opening:

There isn't one better than from the article:

Once upon a time, virtually no Christians denied that Mary the mother of Jesus was perpetually a virgin: including Protestants. Of the early leaders of that movement, virtually all fully accepted this doctrine: including Luther, Calvin, Zwingli, Bullinger, and Cranmer. Moreover, most Protestant exegetes continued to believe it for at least another 350 years or so. But today (for various reasons) things are very different, so it’s helpful to revisit the biblical arguments, since the Bible is the authority all Christians revere in common. A surprising number can be found: so many that they will require more than this article to highlight the major ones: even in summary.

1. Mary's answer to the angel.

Luke 1:34 (NRSVCE)¹
34 Mary said to the angel, “How can this be, since I am a virgin?”[a]

Footnotes:
a. Luke 1:34 Gk I do not know a man

This question does not make any sense at all if Mary and Joseph after marrying, would have had marital relations.

2. Under John’s Protection.

Point 5. in the article The Blessed Virgin Mary is committed to the care of the Apostle John by Jesus from the Cross (John 19:26-27). Jesus certainly wouldn't have done this if He had brothers (all of whom would have been younger than He was).

3. The Power of the Most High overshadowing Mary.

Luke 1:35 (NRSVCE) 35 The angel said to her, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born[a] will be holy; he will be called Son of God.

Footnotes: a. Luke 1:35 Other ancient authorities add of you

From Ezk 16:8 (RSVCE) and Ruth 3:9 (RSVCE) and from this explanation [t]t is possible that spreading of the garment over a woman was a more primitive form of marriage in Adoption | Jewish Encyclopedia, it is clear why among Catholics Mary is referred to as the Spouse of the Holy Spirit. With this understanding, it is impossible for even the thought to have entered the just man Joseph to approach Mary [as a man goes to his wife] after the Holy Spirit coming upon her. I remember this making a deep impression on me the day a priest explained it to me.

“Lo, having me my master has no concern about anything in the house, and he has put everything that he has in my hand; he is not greater in this house than I am; nor has he kept back anything from me except yourself, because you are his wife; how then can I do this great wickedness, and sin against God?” cf. [Gn 9:7-11 (RSVCE)].

V. To Saint Joseph, Spouse of the Blessed Virgin Mary.
R. God made you like the Father of the King and Lord over his household: pray for us.

The readers are invited to go through the other arguments in the article.

Closing:

Marital sex, as wonderful as it is, is a type of the heavenly union that is to come. With Jesus, Mary and Joseph had heaven. It is also easy to understand that celibacy goes back to the Apostles.

Regarding Mary, one of the reasons that her children thank the LORD and are proud of her is that at least one of us [humans] never fell under the power of the devil.

You are the glory of Jerusalem ... you are the splendid boast of our people ... God is pleased with what you have wrought. May you be blessed by the LORD Almighty forever and ever. [cf. Jdt 15:9-10].

cf. Protestant arguments for perpetual virginity of Mary and apologetics - perpetual virginity of Mary.

1. [Luke 1:34 (RSVCE) “How can this be, since I have no husband?” puzzles even more given the two stages in Jewish marriage and considering that the betrothed were considered husband and wife and could have marital relations.]↩

There is one ancient source which lists Joseph as a widower and that the "brothers of the Lord" were only half(??? step???) brothers of Christ. It does not appear to be a listing of the number of wives that Joseph had, simply that he had had at least one (and thus "widower").

There are those, however, who would say that Joseph was similarly celibate and that the words, "brother" and "sister" are better understood as "kinsman" and "kinswoman."

There is no source in the bible (or anywhere else that I know of) which states how many other wives Joseph had. There are many a scripture which talk about Jesus's 'brothers. (Mt 12:46, Mk 3:31, Lk 8:19, Mk 6:3) which is troublesome, but the notes in my bible read thus:

In semitic usage the terms 'brother' and 'sister' are applied not only to children of the same parents, but to nephews, nieces, cousins, half-brothers and half sisters; cf Gn 14:16;29:15.

While one cannot suppose that the meaning of a greek word should be sought in the first place from semitic usage, the Septuagint often translates the hebrew 'āh by the Greek word adelphos, "brother," as in the cited passages, a fact that may argue for the similar breadth of meaning in some new testament passages. For instance, there is no doubt that in [mark 6:17] , "brother' is used of Philip, who was actually the half-brother of Herod Antipas. On the other hand, mark may have understood the terms Literally; see also Mt 3:31-32, 12:46, 13:55-56, Lk 8:19; Jn 7:3, 5 The question of meaning here would not have arisen but for the faith of the church in Mary's perpetual virginity.

That passage is taken from a note on the text of Mk 6:21 (NAB)

Other then biblical commentary, I know that since life didn't last very long 2000 years ago, it was very possible for Joseph to have had a wife or two before Mary --its entirely plausible that they simply died before the beginning of our Gospels, and the children of these women end up living in the same House or community as Jesus.

This way, we can reconcile the text of 'brothers' with the Perpetual Virginity of Mary (which not every christian acknowledges...)

Also, I am pretty sure I read somewhere that Augustine held an opinion similar to the above. Just saying...

There is no reconciliation needed. The Bible is the perfect inerrant Word of God. Scripture interprets Scripture and Mary the mother of Jesus did not remain a virgin after Jesus' birth and had other sons and daughters. Let no one pervert the Word of God or lean on their own understanding. To read into the Bible anything else or draw from non Biblical texted outside the Bible is false doctrine and untrue. Amen

"And Joseph awoke from his sleep and did as the angel of the Lord commanded him, and took Mary as his wife, but kept her a virgin until she gave birth to a Son; and he called His name Jesus." Matthew 1:24-25

"Is not this the carpenter's son? Is not His mother called Mary, and His brothers, James and Joseph and Simon and Judas? "And His sisters, are they not all with us? Where then did this man get all these things?" Matthew 13:55-56