prieldedi: It seems like it has become not so much an issue of whether Mary was or was not a perpetual virgin, but rather, whether Jesus passed on through His disciples, that she was, and ALL must believe in the fact that she was to be saved

To presume what Jesus or for that matter God MAY have said is treading on dangerous ground

You can probably convince of her perpetual virginity; but her being a part of salvation, is a major stretch! Look, we know that apostolic successors have taught many things, seemingly passed down from Jesus, through chosen men, who may or may not have changed a word here or there; but until now, I have never heard of the theory that in order to be completely saved, one must believe that Mary was a perpetual virgin
There is no end to this. At this point it seems you argue for the sake of arguing. I mentioned that God can have you accountable “for not believing the ones He sent you and told you about Mary’s Perpetual Virginity.” Can you see the difference?
If we are to argue, instead of arguing whether Jesus passed on through His disciples that Mary was Ever Virgin, shouldn’t we be arguing if Jesus asked His disciples to write down the Gospels in the first place? Non Christians say that the Apostles themselves “may or may not have changed a word here or there” too. Be careful to attack the integrity of the Church, it might backfire on you.
OK, let me try from another angle and this is about the thread, Mary’s Perpetual Virginity:
Was there anyone else that could have explained Mary’s Perpetual Virginity to the Apostles, if Jesus didn’t? Yes, MARY Herself!
Do we know who told Luke the sentence “How can this be if I’m a Virgin”? MARY!
Is it possible that Mary “explained” to Luke what “I’m a Virgin” really meant? YES!
How long did Mary remained on earth after Pentecost? YEARS!
Who were around Mary all those years? THE APOSTLES!
Were all the conversations between Mary and the Apostles “RECORDED” in the Bible? NO!
Does the fact that all Her conversations with the Apostles were not recorded in the Bible mean they never took place? NO!
Is it possible that Mary had a greater role in the writing of the Gospels than previously thought? YES!
How? Matthew, Mark, Luke and even the other writers showed Her, asked Her if what they wrote was right. After all, who is the person that was at Jesus side ALL THE DAYS OF HIS EARTHLY LIFE, right up to the moment that He ascended to the Heavens, and could have known details of Jesus’ and Her life that others didn’t know? MARY!
Was it necessary for the writers to write down Her Perpetual Virginity? No, they didn’t to protect Her and Her Son’s Divinity.
Protect Her, Him? Why? Jesus enemies know that if they can destroy Her first it would be easier to destroy Him afterward. Nazis in Germany spread the fable that Jesus was “blond” (Nazis hated Jews), and that his father was actually a Roman soldier recruited from the northern end of the Roman Empire (today’s Germany), and was assigned in Jerusalem by the time of Jesus birth. This happened 1900+ years after Jesus birth, imagine what the enemies of Jesus would have said about Him and Mary if her Perpetual Virginity was “preached” to them! By looking at your own reaction I can picture the scene clearly!
God bless you