The following information was supplied in a post-em by Curt Hofemann, curt_hofemann@@yaho.com:
Helewise, mar. Robert fitz Ralph (d. 1184-5), lord of Middleham, Yorkshire, and had 3 sons: Waleran (b. c.1170 [16]), Ralph, Ranulf. Helewise was said to have d. 1 Mar 1194/5, bur. Swainby abbey, Yorks. (her foundation, later moved to Coverham, Yorks.) [Ref: Raymond Phair <rphair@@CapAccess.org> message to soc.genealogy.medieval 22 Feb 1999]
Helwisia de Glanville, the third daughter of Lord Ranulph de Glanville, married Lord Robert Fitz Randulfi, Baron of Middleham, from whom descended the family of Neville, Earls of Warwick...
At a distance of three miles from Jervaux, Yorkshire, lie the scattered remains of the Abbey of Coverham. This house was of Praemonstratensian Canons, first founded in Swainby, in the parish of Pickhill, by Helewisia de Glanville, upon the lands in the lordship of Coverham, which had belonged to her father.
In the year, 1214 Ralph Fitz Robert, her son, translated the Abbey from Swainby to Coverham, near to his manor-house at Middleham, where an abbey was built and flourished until 1538, the gross annual value then being £207 14s. 7d. Helwisia was buried at Coverham; the issue of this marriage was three sons, two of whom died without issue, but the third, Ralph Fitz Robert, married Mary, daughter of Roger Bigod, [fn 66] Earl of Norfolk, and by her had issue two sons, the elder, Ranulph Fitz Ranulph, Lord of Middleham, married Anastacia, daughter of William de Percy, and he dying in 1270, left Mary, an only daughter, and sole heiress, both to the Glanville and Middleham property. She married Ralph Neville, Lord of Raby, who, dying in the 55 of Henry III., was succeeded by his son, Ralph Neville, Baron of Raby, who now represented the Lords of Middleham and a branch of the House of Glanville. [Ref: http://ourworld.compuserve.com/homepages/jglanville/roanhg4.htm]
VHC Yorkshire North Riding, vol. i, ed. by William Page:
pp. 218-219: "At COVERHAM, where 4 carucates of land were at geld, the two 'manors' held by Tor and Egbrand before the Conquest were in 1086 held by Count Alan in demesne. The count's younger brother Ribald was already tenant of 3 carcates of land in Scrafton, but Coverham, according to an 'old roll' transcribed by Dodsorth, was acquired by his descendant Robert, who married Helewise daughter and co-heir of Berta daughter of Theobald de Valoignes the elder by her husband Ranulph de Glanville, Chief Justice of England and lord of Coverham. Helewise died in 1195 and her son and heir Waleran gave the church of Coverham to the abbey founded by his mother at Swainby in the parish of Pickhill (q.v.). The abbey, however, was removed to the bank of the Cover by Ranulph, brother and heir of Waleran, in 1212. To this spot the bones of Helewise were removed, and here the subsequent lords of Middleham found burial."
p. 378. "The Premonstratensian abbey of Coverham was first founded at Swainby by Helewise the daughter of Ranulf de Glanvill, but was removed to Coverham by her son Ralph." [Ref: Alan B. Wilson <abwilson@@uclink2.berkeley.edu> message to soc.genealogy.medieval 2 May 1998]
Turton (following W U Glanville-Richards *Records of the House of Glanville* (1882) - not a work well thought of by the DNB) makes Helewise daughter of Ranulph de G rather than his sister [Ref: Richard Borthwick <rgbor@@cyllene.uwa.edu.au> message to soc.genealogy.medieval 1 Sep 1998]
Regards,
Curt
Note: Even though Richard Borthwick, seems to question whether Helewise was daughter or sister of Ranulph, the other sources, including the well-respected VHC (which is based on original documents), seem to concur with Turton.