It is unknown what the children’s given names are, however, it is likely/possible that the elder girl shares her mother's mysterious M. name and the elder of the two boys is named Edward as Jane Austen frequently named eldest sons after their fathers and eldest daughters after their mothers.
Ages: The two girls are 6 and 8. The two boys are younger.
Other information: We really don't know much about them. Their cousin Jane is their general favorite and they are both excited and shy when their cousin Elizabeth visits, having not seen her in about a year. They do not accompany their parents to Longbourn at Christmas or on their tour of Derbyshire (during which they are left in the care of their cousin Jane).