Sources

1) Source: Chancery: Inquisitions Post Mortem, Series I, Edward II "ROGER BERTRAM alias BERETREM, DE BERTRAM...He had one daughter Agnes, who died without heir. Philip Darcy, Elias de Pannebiri, and William, son of William de Emeley, each aged 30 at least, are now his next heirs...The said Roger had four sisters:—Agnes de Emeley, Isabel Darcy, Christiana de Ros, and Ada de Veer; from Agnes came William son of William, and from him William that now is; from Isabel issued Norman Darcy, and from him Philip Darcy that now is; from Christiana issued Elias de Penbury that now is; and from Ada issued Isabel, and from her Gilbert de Aton’ that now is; which William, Philip, Elias, and Gilbert are next heirs of the said Roger and Agnes." Date: 1310 Roger's children are all listed in his son's IPM.. External Link
https://www.british-history.ac.uk/inquis-post-mortem/vol5/pp164-176. Reference: C 134/23/14 (Data from secondary evidence)
2) Source: Chancery: Inquisitions Post Mortem, Series I, Edward II "ROGER BERTRAM alias BERETREM, DE BERTRAM...He had one daughter Agnes, who died without heir. Philip Darcy, Elias de Pannebiri, and William, son of William de Emeley, each aged 30 at least, are now his next heirs...The said Roger had four sisters:—Agnes de Emeley, Isabel Darcy, Christiana de Ros, and Ada de Veer; from Agnes came William son of William, and from him William that now is; from Isabel issued Norman Darcy, and from him Philip Darcy that now is; from Christiana issued Elias de Penbury that now is; and from Ada issued Isabel, and from her Gilbert de Aton’ that now is; which William, Philip, Elias, and Gilbert are next heirs of the said Roger and Agnes." Date: 1310. External Link
https://www.british-history.ac.uk/inquis-post-mortem/vol5/pp164-176. Reference: C 134/23/14 (Data from direct source)