Gilbert FitzRoger FitzReinfrid
Gilbert FitzRoger was born before 1185.  He died before June 13th, 1220.

 Helwise de Lancaster
Helwise was born before 1184.  She died after September 1226.

 Avice FitzGilbert de Lancaster
Avice FitzGilbert was born before 1221.

 Helwise FitzGilbert de Lancaster
Helwise FitzGilbert was born before 1221.

 William III de Lancaster
William III was born before 1221.  He died on November 20th, 1246.