Supposing that she had children other than Christ, do you think they loved her any less that they didn't deserve her, or that for some reason they couldn't or wouldn't take care of her?
Besides, it was a matter of law. Christ was a condemned criminal. There were no witnesses that He "gave" her away. +John, a follower of a condemned criminal, was not in a position to make any claims. The Jewish and Roman law would have prevailed. The children would have claimed her.
There were no "other" children. No one claimed Mary. Our Lord knew that when He dies she will be alone, so He gave her to the only disciple who was brave enough to be with Him at the Cross.
Not only are you implying that she had a bunch of children that took her attention away from her real Son, but you are also implying that because they were not believers they were not "worthy" of their mother! And, in the same vain, you are assuming that they didn't love their mother enough to want her.
Not only are you implying that she had a bunch of children that took her attention away from her real Son, ...
Mary's mind was not always one with the mind of Christ ...Mark 3:21,31-34
When his family heard about this [i.e. that Jesus was preaching to a crowd] they went to take charge of him, for they said, "He is out of his mind."
...
Then Jesus' mother and brothers arrived. Standing outside they sent someone to call him. A crowd was sitting around him, and they told him, "Your mother and your brothers are outside looking for you." "Who are my mother and my brothers?" he asked. Then he looked at those seated in a circle around him and said, "Here are my mother and brothers! Whoever does God's will is my brother and sister and mother."
...but you are also implying that because they were not believers they were not "worthy" of their mother! And, in the same vain, you are assuming that they didn't love their mother enough to want her.
The claims of Christ and his teachings drove a wedge through Jewish society, ... even through the midst of some families ...Matthew 10:34 Think not that I am come to send peace on earth: I came not to send peace, but a sword.
35 For I am come to set a man at variance against his father, and the daughter against her mother, and the daughter in law against her mother in law.
36 And a man's foes shall be they of his own household.
And his parents went every year to Jerusalem, at the solemn day of the pasch, And when he was twelve years old, they going up into Jerusalem, according to the custom of the feast, And having fulfilled the days, when they returned, the child Jesus remained in Jerusalem; and his parents knew it not. And thinking that he was in the company, they came a day's journey, and sought him among their kinsfolks and acquaintance. And not finding him, they returned into Jerusalem, seeking him
*So, seeing as how men travelled with men and women with women, it appears Jesus had no brothers to say, "Hey, where is Jesus?"
* I suspect Mary did have 15-30 daughters but they all died during the Great Jerusalem Flu epidemic of 31 ad.
What relevance did Christ's status as a condemned criminal have in comparison to His status as Lord, in terms of the authority He exercised in tasking John with Mary's care?
Of course, +John made no claims. Jesus informed him of what his free will would be. :) That's what the scripture says.
Where does Jewish Law say that the other children would have "made a claim" AGAINST a widowed mother who was already provided for? (And what would Roman law have to do with this?) Note that your scenario presumes that the children would have fought the decree of Jesus. Why would they have done that, Jesus was the oldest?
What do you mean by "witnesses"? While Mary was of course not male, she was the matriarch, and she was the only believer. I think her own testimony in front of her children, who all RAN (or never showed up at all), would have counted for something. It was only HER life. :) Mary was at the cross and suffered greatly. Would you have questioned her witness as to what our Lord said while nailed and dying on a cross, while you were hiding? I don't think they would have questioned their mother either. :)