Henry I (c. 1100), wife Berta, son Engenulf, son Robert (does the W go with E or R, or its own person?)
Monasticon Anglicanum
Coventry Monastery
NUM VI (Willielmi I): Henrico de Ferrariis
Tutbury Priory
NUM I: Henricus de Ferariis, exoris meae Bertae (wife), filiorum meorum (sons) Eugenulphi, W. Roberti, filiarum mearum (daughters)
Robert I (c. 1139), father Henry
Monasticon Anglicanum
Burton upon Trent Monastery
NUM VI (Henrici I): R de Ferrariis
Tutbury Priory
NUM VI: R. comes de Ferrariis
NUM XI: Robertus comes de Ferrariis, Henrici patris mei (father)
Abbey of Merebal
NUM II (Henricus rex): Robertus de Ferrariis
Calendar of documents preserved in France
Abbey of St Pierre-Sur-Dive
580 (1135-1139): Robert de Ferrariis
Robert II (c. 1158), father Robert, grandfather Henry, grandmother Berta, uncle Engenulf, mother Hawice
Monasticon Anglicanum
Tutbury Priory
NUM II: Robertus comes junior de Ferrariis, avus meus Henricus (grandfather), Berta uxore sua (his wife - Henry's), Egennlfus patruus meus (uncle), Robertus pater meus (father)
NUM VII: Robertus junior, comes de Notingham
Abbey of Buildewas
NUM I (Stephanus rex, 1135-1154): Robert de Ferrariis
Calendar of documents preserved in France
Abbey of St Pierre-Sur-Dive
581 (1140-1150): Robert the younger earl of Nottingham, grandfather Henry, uncle Engenulf, father Robert
582 (1141): Robert the younger earl of Nottingham, mother Hatwis
Abbey of Savigny
806 (c. 1140): Robert earl Ferreres
824 (1157): Robert earl de Ferreriis
William II (c. 1191), wife Sybil, father Robert, grandfather Robert, great-grandfather Henry, brother Robert
Monasticon Anglicanum
Tutbury Priory
NUM IV: Willielmus comes de Ferrariis, Henrici de Ferrariis proavi mei (great-grandfather), Eugenulphi de Ferrariis, Roberti avi mei (grandfather), Roberti patris mei (father), uxoris meæ Sibillæy (wife)
Calendar of documents preserved in France
Abbey of St Pierre-Sur-Dive
583 (1158-1159): William de Ferrariis
584 (1158-1159): William earl Ferrars, William de Ferrariis his kinsman, R de Ferrariis fratre comitis (brother), R de Ferrariis proavo ejus (grandfather), Thoma de Ferrariis (relation not mentioned)
586 (c. 1170): William earl Ferrars
Cathederal Church of St Mary, Bayeux
1446 (1177): Willelmus de Ferrariis
National Archives (CRU/923): Gift by William de Ferariis, witness Roberto de Ferariis fratre meo (brother)
William III (c. 1247), father William, wife Agnes Meschines, brother Thomas, grandmother Margaret Peverel, mother Sybil de Broase, stepfather Adam de Port
Monasticon Anglicanum
Tutbury Priory
NUM V: Willielmus comes de Ferrariis, filius (son of) Willielmi comitis de Ferrariis
NUM VIII: Willielmus comes de Ferrariis, filius (son of) Willielmi comitis de Ferrariis
Calendar of documents preserved in France
Abbey of St Pierre-Sur-Dive
589 (c. 1200): William de Ferrariis, earl of Derby, Agnes his wife, Thoma fratre meo (brother)
Priory of St Stephen, Plessis-Grimould
566 (25 Sep 1203): W comite de Ferrariis
Plea Rolls for Staffordshire: 1231-39
wife Agnes is sister of Chester
Fine R. 1 John, m. 23; Hardy, Rot. de Oblat. et Fin. p. 3; Pipe R. 1 John, m. 2d
grandmother Margaret is sister of Peverel
from Rymer, f. 143, A.D. 1212, 14 John
nephew of William de Broase, whose sister married Adam de Port
Most of the documents I'm finding line up with what we've got, for the Derby line, for the most part. Unless the documents mentioning a brother, Robert, for William I, should actually be attributed to William II, then we should add a brother, Robert, for William I, rather than a brother Walkelin. (That Walkelin, who marries a Goda, has been conflated with brother William who died at Acre, and possibly Walkelin fitz Gerard of Derby, who married a Goda. I haven't found any evidence of a brother Walkelin, nor a marriage to a Toeni.)
Contradictory documents:
Monasticon Anglicanum
Abbey of Dore
NUM I: Robertus* comes de Ferrariis, "Sibillae de Braosa, exoris meae (wife), matris W. filii mei (mother of my son William), et sua, et pro salute Bertae (fuit filia Milonis comitis Herfordiae) matris uxoris meae (mother of my wife)"
*FMG states [mistake for Willielmus], which then makes it compatible with everything else.
Calendar of documents preserved in France
Abbey of St Pierre-Sur-Dive
585 (c. 1160): William earl Ferrars, Roberto de Ferrariis fratre comitis (brother), Robert et Henrico de Ferrariis ejus patruis (uncles)
I looked at the possibility of this being dated incorrectly, but the witnesses seem to suggest the date is about right. I also tried inserting an extra generation, to make it compatible, but that just caused more contradictions with other sources. I haven't found an original online, to double check what it says.