Ellen fitz Elias, Heiress of East Cowton - Evidence for parents

'A History of the County of York North Riding: Volume 1', William Page, 1914 (british-history.ac.uk/vch/yorks/north/vol1/pp160-162), tells us that
Conan (son of Elias {Ellis/Elie/Helias} but also son of Theophania, the daughter of Roald the Constable and Garsiena his wife) held the manor of East Cowton from the time of King Stephen (i.e. before 1154) to about 1200. Conan was probably seneschal of the lord of Richmond.
Conan had no children, and his inheritance was divided between his aunts Beatrice, Parnel and Constance.
William de Lascelles, son of Parnel {who was married to Picot de Lascelles}, and Elias de Crakehall {near Bedale}, son of Constance, granted their parts to their heir Sir Richard Fitton {snr.} of Bollin in Cheshire.
But there is no indication of a positive blood-link to Sir Richard Fitton. Why is he heir?

I believe this Sir Richard Fitton, of Bolyn

https://www-personal.umich.edu/~bobwolfe/gen/mn/m31711x31712.htm

The IPM for Richard Fitton states, [2]

841. Richard Fitun.
Writ (missing). Inq. (undated.)
Hugh Fitun, knight, is his heir.
Chester. Bolyn manor. 2 bovates land and a mill, with the advowson, held of the king in chief by service of coming to the army at Chester with all his household (cum tota familia sua) with horses and arms at the king's expense.
Falinisbrom, held of the king in chief by 3s. rent. (See Rot. Fin.
30 Hen. III. m. 7.)
C. Hen. III. File 43. (14.)

Footnotes:

[1] J. P. Earwaker, East Cheshire: Past and Present; or A History of the Hundred of Macclesfield, in the County Palatine of Chester Vol. 1 (London, Printed for the Author, 1877), 43, [HathiTrust].

[2] Calendar of Inquisitions Post Mortem, Vol. 1, Henry III (London: HMSO, 1904), 290, [GoogleBooks], [HathiTrust].