Is him being a descendant of Solomon accepted as fact or is it only speculated to be the case? Is this based off of the section in 1 Kings chapter 2 verse 4, where David tells Solomon how G-d promised him that there will always be someone of his line on the throne, as long as they follow G-d?
The thing is, David doesn't mention Solomon by name here. So if you take it at face value, it's talking about any descendant of David. Solomon wasn't the only surviving son of David with progeny, right?
Is there another passage that cements Solomon's role as the Messiah's ancestor? If there is, then how do we know that the Messiah would come from Rehoboam's line? Solomon probably had tons of children besides him.
Edit: Since this is technically a duplicate, can anyone answer the part about Rehoboam in the original question that has been linked up top?