Everything Throne of Glass and ACOTAR

Gavriel and Aedion

So I was thinking about Gavriel being Aedions father and suddenly everything just clicked.

I'd spent AGES wondering why Aelin was heir to the throne of Terrasen and not Aedion (since he was older) and then I realised that he isn't actually related to the past king of Terrasen.

So I don't know if this is common ToG knowledge or not, but I realised that their mothers (I don't remember names) must have been sisters, and that Alein's uncle was the king, but he wasn't Aedions uncle...

Why has it taken me so long to realise this?

But how are they related to Galan, can someone please explain to me because I'm so confused!!!