Now, on to miracles. How would a claimed miracle in the past, be verified as true by a historian employing the historical method?
I'm not trying to circumvent any rules here. I'm willing to answer your question, but if this thread gets shut down as well, I suppose that means we need to take this offline.
First of all, I do not recall one thing you mentioned ever being generally accepted as part of a historical method. That being your comment that a historian must dismiss a claim if it is not the most parsimonious explanation. A cited expert may include that in their argument, but the historian himself is under no such obligation.
That leads into a second point, which is what appears to be your mistaken idea that historians sit in judgement like some kind of panel that has been given authority to declare historical truth. Such is not the case. Historians evaluate claims, and that evaluation includes addressing all sides of the issue. Yes, there are "facts" that are not in dispute. But the reason they are not in dispute is simply because no one is disputing them. If someone does dispute a claim, historians move into the claim/warrant process, but there is no aspect of that process which insures an undisputed conclusion can be reached.
The miracles* of the Bible are disputed. In that process, a certain amount of bluster occurs where historians will make "conclusive new evidence" or "we now know" types of declarations. But if you read carefully, modern peer-reviewed literature will never say "such-and-such miracle is impossible".
So, can a miracle be proved impossible? I would say no.
If we can't prove it impossible, we must accept it as possible.
If we must accept it as possible, a historian should not dismiss the miraculous claim without evidence specific to the event.
Historians have no evidence specific to the claimed miraculous events in the Bible.
Therefore, historians should not dismiss them. They can offer alternative explanations if they choose, but they should not dismiss them as impossible.
*Footnote: Since no definition of "miracle" has been given for this thread, I'll offer mine (which is actually that of C.S. Lewis). A miracle is not a suspension of physics, but God's intervention in the world using a power larger than that available to humanity.