Here are some primary documents:
Calendar of Patent Rolls
1283, 17 Dec
Simple protection, for two years, for Griffin de Warenna.
Calendar of Fine Rolls, Edward I, p. 198
1284, 24 January
Order to the same to take into the king's hand the lands late of Griffin de Warenna, deceased, tenant in chief.
1287, 12 February
Grant, for a fine of 100s, to Isabel, late the wife of Griffin Warren, tenant in chief, that she may marry whomsoever she will in the king's feilty.
Drakeslowe, feast St. Micheal, 24 Edw III
Griffith de Warrenna paid rent for lands in Overmestrch
Cal. Pat. Rolls, Ed III, vol. 10, p. 428
1356, July 16 Westminster
Licence, for 10l, to be paid to the king by Griffin de Warenne, for him to enfeoff William de Botefield, clerk, and William de Ightefeld of the manor of Ightefeld (2 acres of land therein excepted), which is held of the king in chief and for them to grant the same to him for life, with remainders to Griffin son of John son of Griffin and Elizabeth, his wife, in tail, and to the right heirs of the said Griffin de Warenne. And the 10l have been paid in the Hanaper.
Calendar of inquisitions Miscellaneous, vol. 3, p. 138
Writ to the sheriff of Shropshire, 2 March 33 Edward III 
Inquisition, Thursday aft. Palm Sunday.
Griffin de Warenna holds in fee the manor of Ightfield, which is worth 20 marks yearly, and nothing else which can be extended at present.
Transactions of the Shropshire Archaeological and Natural History Society, ser. 4, vol. 1, p. 177.
6 Jun 1361, Griffin de Warenna received licence for an oratory at Ightfield.
23 Edward III
Griffin de Warrene served as witness for the ipm of John Lestrange.
Calendar of Inquisitions Post Mortem, vol. 10 (Edward III)
Proof of age, John son and heir of John Lestraunge
Writ, 20 March, 28 Edward III; Proof of age, feast Corpus Cristi, 28 Edward III
Griffin de Warenne, aged 40 years and more, agrees and says that he married his wife Alice in the same year. [6 Edward III]
Ancient Deeds, vol. 5, p. 125
A. 11308 feoffment Sun. bef. Christmas, 48 Edw III witnessed by Griffin de Wareyn, lord of Hightfeld
Cal Patent Rolls, p. 496
1384, 10 July Griffin Wareyn named justice of the peace for Shropshire.
Cal Fine Rolls, p. 71
1384 Griffith Wareyn, collector of taxes
1386 Griffith Wareyn, collector of taxes
1388 Griffith Wareyn, collector of taxes
Pedigrees from the Plea Rolls, p. 170
Chester Plea Roll. No. 89. 9-10, Ric. 2, m. 29.
Cestria - Griffin, son of John de Warenne, sued Roger de Bulkylegh of Broxton and Margery, his wife, for land in Broxton, which Emma, formerly wife of Robert de Pulford, gave to Griffin de Warenne in marriage with Isabela, her daughter.
Griffin de Warenne=Isabell, temp. Ed. 2
Griffin de Warrenne, the plaintiff.
Cal Fine Rolls, p. 264
1398 Griffith Wareyn, collector of taxes
1402 Griffin Wareyn, lord of Ightfield taxed
1402 Griffin Wareyn named justice of the peace for Salop
Calendars of Inquisitions Post Mortem, Henry IV, vol 1
Proof of age of Robert son and heir of Margaret Corbet, 18 March 1405
Griffin Wareyn, 46, had a son of the same age. (testifying that Robert was born 8 Dec. 1383)
Calendars of Inquisitions Post Mortem, Henry V, vol 1, p. 5
IMP of John, son and heir of Griffith Wareyn
Writ 8 June 1413
Inq. 19 June 1413
Held Ightfield in chief
died 4 Feb last, heir Griffin, son & heir aged 13 yrs and more
28 June 1413
Griffin Wareyn held lands in Ightfield of Ankarat, wid Richard Talbot
IPM Griffin Wareyn
Writ 18 Oct 1415
Inq 17 Dec 1415
Held Ightfield, died 5 October last, Margaret, daughter of John Wareyn is his sister and heir, aged 13 and more
proof of age Margaret, daughter of John Wareyn
sister of Griffin, in custody of Philip de Egerton by grant of Roger de Acton, Knt.
bapt 11 June 1401
Taken together, we get the following pedigree:
1. Griffith, d. 1283/4, m. Isabel de Pulford (this assumes the Griffith named in the plea roll from the 1380s with wife Isabel is misdated as being in reign Edw II, when he was actually this man from Ed I)
3. Griffith, b. bef. 1325(?), fl. 1350s, 60s
5. Griffith, fl. 1380s, 90s
6. John, d. 4 Feb 1413
7a. Griffith, b. ca. 1399/1400
7b. Margaret, bap. 11 June 1401
(Note: the span from gen 1 to 3 is a bit long, but given that the '40 and more' of his age usually just means the person is a full adult, he could have been in his 60s, so I still think it likely the Isabel who was widow of Griffith in 1284 is the same as the Isabel who was great-great-grandmother of the plea pedigree.