[A/N:The interesting thing is not all Starks are loveable as the ones from GOT.The Starks in Dance of the Dragon is said to be ruthless and power hungry,it seems that's why south views North as Savages.]
The Lord's Ring was enchanted by the Celebrinbor and Eragon to recognize bloodline like your future heir.The Ring actually uses his enchantments to recognize,if the person is really the son or heir of previous Lord.The Ring had the sigils of there respective families,like Starks had wolf
Of course there are ways for nephew or brothers to become the next Lord,it is basically if the previous Lord does have any living children.Also there protection to make sure that no one tries to unsurprising by killing the previous Lord and Heir,so the Ring will reject them.
If the heir is accepted then he will be automatically or magically entered into a Family Tapestry,which is a tapestry depicting the family tree.Which would contain all there family members and what connection they have with previous Lord like Son,Nephew or brother.
Other family members could enter themselves into the family tapestry by just putting a drop of there blood into it.But this also has enchantments that will recognize,your bloodline so fooling it is not really possible,since it will have the genetic marker of all your family members and ancestors.
The Starks were the first to accept it,since this allowed them to see the family connection to previous Starks.
The Stark Family Tapestry was depicting the family tree. It contained every image of family members dating back to the Bran the builder and Toric Stark.To make sure the Family Tapestry had the genetic marker of every late family members,Eragon had to talk with some of Valar,they more or less agreed Mandos took a while to convince.
Now in Winterfell Arron Stark now was looking at the Stark Tapestry,he had certain nostalgic feeling seeing the images of his father,grandfather and pride seeing his ancestors.
The tapestry had old and ancient feeling. Nevertheless, the white thread with which it was embroidered still glowed brightly enough to show them a sprawling family tree dating back to ages of Bran the Builder. Large words at the very top of the tapestry read "Winter is coming."
Arron muttered"They would have loved it."
Eragon the walked next to him and whispered"Yes, they would,especially you grandfather Harald."
Arron remembered his old grandfather,who was in his prime known as Harald the impaler,it was something unbelievable when he first heard it.
Arron looked at the image of his Harrison Stark,with sadness and thought"If only you were here to see your grandson father."
Eragon sensing the atmosphere asked"How is Torren doing?"
Arron breaking out of his mood replied"He is doing good,but he seems to have a habit of overthinking and being slight paranoid."
Eragon chuckled patting Arron said"Don't worry he will mature with time."
Then the news spread many followed like there Vassals.Then Dorne,Reach,...etc.Only ones who didn't was Storm King,Lannister and there vassals.
But interesting thing was just year into it a scandal broke out about the House of Hightower.It was found that Lord Barris High Towers oldest son was not his,it was huge.
No matter how much the Wife in question tried to blame the North,Barris wanted this to be false so he tried his 3 other sons and each came out without any issue,all three showed to be his bloodline.
Barris went far as to bring The Lineages and Histories of the Great Houses of the Seven Kingdoms, a book detailing genealogies of the nobility, which notes the hereditary preponderance of each houses.
Barris older son had blue eyes and slight sturdy built,while all his other children had slight brownish hair and smaller built.Barris at time didn't note of this,thinking his eldest son got his traits from mother's side of the family
The investigation proved oldest son was not from Barris and his wife as killed and former son exiled it was quite the problem.So the Lord ship rings became a must with time and many started asking the Starks for one,but not everyone got it.
Another thing was some houses rejected it like
House Reyne of Castamere was a noble house from the Castamere in the westerlands.Eragon did little digging and found out the now Reyne family was actually cut off the original bloodline because there son was technically a bastard.
[A/N:Also after next two chapters Aegons conquest starts and North will be separate Kingdom,with Aegon's daughter marrying the Starks.]