All good questions @Biblebeliever, for the focus of the thread though, IMO there are several things that we don’t know and can’t prove within Cannonized Scripture.
- We cannot prove whether or not Joseph had other wives simultaneously with Mary or prior to Mary
- We also cannot prove that he didn’t have another after he married Mary or that he didn’t have a wife and/or children previously.
- All that can be proven is that there were other children that were called brothers and sisters with no mention of who their mother was or their birth order.
- That Mary was definitely the mother of Christ and he was her first.
- That Joseph was intimate with Mary after she brought forth Christ. Some might be able to argue that if Christ was her firstborn then there must be a “secondborn”, however that view IMO is not as airtight as it would seem to be at first glance since that was often used as an idiom for the inheritor. It did not necessarily prove the existence of a second son, just the existence of a first son.