|Father||St. John Cropper|
|Sibling(s)|| Roy Cropper (half-brother) |
Isabelle Cropper was the half-sister of Roy Cropper who resided in Cornwall. Roy was unaware of the existence of his half-siblings until he was informed by his stepmother Margaret when he went to visit at her Blackburn home in May 2013, following the death of his father during the previous February.