John I of Ponthieu
John I of was born before 1147.  He died after 1179.

 Beatrice de St. Pol
Beatrice de was born about 1160.  She died after 1204.

 William III Talvas of Ponthieu
William III Talvas of was born in 1179.  He died at the age of 42 on October 4th, 1221.

 Adele de Ponthieu
Adele was born about 1179.