I feel there were no "other children of Mary".
I feel Joseph had sons and daughters by a previous wife who passed away. There is no way to "prove" this - but many people believe it.
The ProtoEvangelium of James is a non-canonical work which gets some of this right - yet it pictures the Wise Men at the Manger - whereas the Bible says the Magi found the young child Jesus "in a house".
The only time that Virgin Mary is ever in the compnay of James, Jude, 2 more brothers and at least 2 sisters happenned to be the occasion where Jesus' family thought His cheese had slid off His cracker - and people told Jesus "Your Mother and Brothers and Sisters are looking for you" - leading Jesus to say " Who are my Mother - Brothers - Sisters? They who do the will of the Father are my Mother-Brothers- and sisters."
At this incident we assume Joseph has already died. At the crucifixion - Jesus commends Mother Mary's care to the Apostle John - the only one who remained present throughout the crucifixion., and also the only disiciple who lived out a natural lifespan, whereas If Mary truly birthed James-Jude et al - one of them could have taken care of Mary - whereas Jesus in fact commended her to John of Zebedee, and Mother Mary lived with John from then on.
People talk of Cathlic Catholic Catholic Catholic as if there never were such a thing as Greek Orthodox and Coptic - this is erroneous - Catholic were not any OLDER or any more ORIGINAL or "earlier" than Orthodox. If anything, Catholics were the schismatics, breaking away from the several patriarchs.
There is also the fact that ADELPHOI in Greek can mean 'close relative' and need not mean SIBLING.
There is nothing that destroys a "Perpetual Virginity of Mary" - though for me as a Protestant there is nothing that requires it either, but 1500 years of the doctrine before Protestants came on the scene should not lightly be tossed aside.