Burchard de Avesnes
Burchard was born in 1182.  He died at the age of 62 in 1244.

 Margaret I of Flanders
Margaret I of was born on June 2nd, 1202.

 Jean de Avesnes
Jean was born in 1218 in Etroeungt, Nord, France.  He died at the age of 39 on December 24th, 1257 in Valenciennes, Nord, France.