Duke Geoffrey IV Plantagenet Of Brittany
Geoffrey IV was born on September 23rd, 1158.  He died at the age of 27 on August 18th, 1186.

 Duchess Constance De Brittany
She died in September 1201.

 Arthur Plantagenet
Arthur was born in 1186.  He died at the age of 17 in 1203.

 Emma Plantagenet Of Brittany