Currently Discover only allows siblings to be linked by Mum or Dad's details matching another child. Often children don't have their parents as contacts and are raised by another family member such as Grandma and we would like to be able to link the children. The only way to do this currently is to change Grandma on all children to be "mum", so Discover recognizes a parent, link the siblings then go back in to each child and change it back to Grandma.