Sam and Robb swap places
Let's suppose that in the midst of Robert's Rebellion, Cat gave birth to a Stark-looking boy whom she named Samwell. And that, in contrast, Melessa Florent gave birth to a Florent-looking boy whom she named Robb.
Both grew up as heirs in a martial culture, but since Ned is a much better father than Randyll, I highly doubt Sam would have a hard time. He's still forced to train, but he isn't humiliated.
Randall, for his part, has the heir he always wanted. He's even more than satisfied because he recognizes Robb's skill as a strategist early on.
What do you think would happen in this scenario? Would Ned allow his heir to become a maester? Or would he convince him to be the heir despite his dislike for martial training?
Otherwise, he would get along very well with Sansa, and it's likely that Jon would be his protector.
Robb, for his part, would be better off, although he would be Paxter Redwyne's squire, perhaps betrothed to Desmera, and isolated with Paxter during the War of the Five Kings. He might even accompany the twins to King's Landing and remain there as a hostage.
In any case, he would maintain a good relationship with his siblings, especially Dickon.
So, what do you think or suggest?