How does Dickens use A Christmas Carol to explore ideas about family?

Dickens explores family relationships in A Christmas Carol both through Scrooge's nephew's family and the Cratchit family.
In the case of Scrooge's nephew, Fred, not only has Scrooge nearly forgotten that Fred is the son of his only and beloved late sister, but he initially refuses to spend time with him.  Scrooge does not accept any invitations to dine with his nephew and his nephew's wife, including the recent invitation to celebrate Christmas. I believe Scrooge cannot accept that despite not having much money, his nephew is very happy with his life. Scrooge eventually joins the celebration after his redemptive visits from the three ghosts.
Bob Cratchit's family is an extreme example of people loving each other, working together through adversity, and being genuinely happy, even in very trying circumstances. The Cratchits have very little, but they celebrate Christmas together in a very thankful, appreciative way. The words of Tiny Tim, "God bless us, everyone," best show the family's attitude of good wishes for all.
Dickens, in his very descriptive way, contrasts the miserly and unhappy life of Ebenezer Scrooge with the lives of two families that have much less wealth but much more joy than him.