Well, the name similarity would normally suggest that, but in this case, we know differently. House Jordayne is named in honor of the late Robert Jordan, sci-fi and fantasy author – its castle, the Tor, is named after Jordan’s publisher, the current lord’s first name is Robert spelled backwards, its sigil is a pen, etc.
I don’t see why the Doylist explanation for its existence should rule out a possible Watsonian reason for its existence?
Ok, here’s the Watsonian reason why that’s not the case.
- House Dayne is a First Men House: “At the mouth of the Torrentine, House Dayne raised its castle on an island where that roaring, tumultuous river broadens to meet the sea. Legend says the first Dayne was led to the site when he followed the track of a falling star and there found a stone of magical powers. His descendants ruled over the western mountains for centuries thereafter as Kings of the Torrentine and Lords of Starfall.” (Dorne – Kingdoms of the First Men)
- House Jordayne is an Andal House: “Elsewhere in the realm, the Allyrions, the Jordaynes, and the Santagars carved out holdings for themselves.” (Dorne – The Andals Arrive)
- The Jordaynes were not vassals of the Daynes, but rather vassals of the Yronwoods: “For nine years Mors Martell and his allies (amongst them House Fowler of Skyreach, House Toland of Ghost Hill, House Dayne of Starfall, and House Uller of the Hellholt) struggled against Yronwood and his bannermen (the Jordaynes of the Tor, the Wyls of the Stone Way, together with the Blackmonts, the Qorgyles, and many more), in battles too numerous to mention.” (Ancient History: Ten Thousand Ships)
- The Tor of the Jordaynes is more than 600 miles distant from Starfall, in a completely different region of Dorne.