In the first chapter of The Lion, the Witch, and the Wardrobe the children see him for the first time, so it would seem that they did not know him before, making it highly unlikely that they are related. But whether he was a relative of the children or not is not stated.
In the professors house
The house had a mysterious wardrobe that served as a portal to the magical land of Narnia when entered. Despite its ordinary appearance, the wardrobe was the key to the children's adventures in the story.
"Evacuating London" by Harry Gregson-Williams
At the end of The Lion, the Witch and the Wardrobe, the children are hunting game and they find an old lamppost. This triggers the memory of how they got to Narnia and the children begin exploring. Their exploration leads them through the woods, to the wardrobe and back to the professor's house in England.
Isnt it Littleroot town?
That he was planning to take over Narnia
The children decided to visit the White Witch's castle first in Narnia.
The professors name in Narnia the Lion Witch and the Wardrobe is "Professor Kirke."The only professor I am familiar with is Digory throughout all 7 books of the series of the Chronicles of Narnia. The only book in which he is not a university professor is The Magician's Nephew, when he was wretched magician uncle's nephew who went to Narnia to rescue Polly as a child. After that book, he had grown up, inherited that huge house, planted the apple core from Narnia that Aslan had allowed him to take home to heal his ill mother, which grew into a huge apple tree, then one day blew down. He couldn't bare to burn it for firewood so he had the wood made into a beautiful wardrobe to put in his house upstairs. And that was the origin of the Narnia wardrobe. The little boy Digory, who went to Narnia to rescue Polly who had taken a yellow ring from his evil uncle and been sent off into who knows where alone with no one to get home, had had the courage to take another ring from his cowardly uncle so he could go to rescue his friend and neighbor Polly. So this is the little boy who later becomes the older knowledgeble uncle who knows about Narnia and isn't skeptical with the later Pevensie children tell him that he wouldn't believe them. He resplies, "Try me!"
Through their grandfathers wardrobe that was in a spare room in his house
Narnia is about 4 children that are orphans some people offer to take care of them and take them to their house where they discover a wardrobe and go inside and come out into the world of Narnia and that's all I'm going too tell you
Lucy Pevensie is the youngest Pevensie child. She is the first of them to discover the land of Narnia when she slips through the magical wardrobe in the professor's house
In C.S. Lewis's "The Chronicles of Narnia" series, the Pevensie siblings discover the magical world of Narnia by entering through a wardrobe in a spare room of the house. The letters do not play a significant role in the Narnia series.