From David Copperfield by Charles Dickens
He was full of eloquence. He gave us to understand that in our children we lived again, and that, under the pressure of pecuniary difficulties, any accession to their number was doubly welcome. He said that Mrs. Micawber had latterly had her doubts on this point, but that he had dispelled them, and reassured her. As to her family, they were wholly unworthy of her, and their sentiments were utterly indifferent to him, and they might—I quote his own expression—go to the Devil.
Does "in our children we lived again" mean we are survived by our children when we are gone or we see in them ourselves? And lastly, does "accession to their number was doubly welcome", refer to asking money from their own children or Mrs Micawber's family?