All of the sources found indicate that Ellen Acclom was the daughter of either John or Richard. Sources which identify John as her father include: Foster(1874) [
https://archive.org/details/pedigreesofcount03fost/page/n263/mode/2up pg. 263-4]: mar. lic. 15 Nov 1493; Ellen as daughter of John Accolm of Moreby; Brain Pames 2nd wife.]
Burke's Commoners (1834)
Burke, John. ''A genealogical and heraldic history of the commoners of Great Britain and Ireland. 1835-38''. Vol 1. Archive.org, [
https://archive.org/details/genealogicalheral01burk/page/612/mode/2up pg. 612] (Palmes - married first Ellen, daughter of John of Morby)]
History of Parliament Online (1982)
Palmes, Brian (by 1467-1519), of Naburn, Yorks. Published in The History of Parliament: the House of Commons 1509-1558, ed. S.T. Bindoff, 1982. Online at {
https://www.historyofparliamentonline.org/volume/1509-1558/member/palmes-brian-1467-1519 History of Parliament Online]: calls Ellen daughter of John Acclom of Moreby
Wikipedia (last edited 2020)
://en.wikipedia.org/wiki/Brian_Palmes_(died_1519)
The only pedigree naming John as Ellen's father appears to be that of Joseph Foster. However, pedigrees naming Richard as Ellen's father include Dugdale,
https://archive.org/details/dugdalesvisitati03dugd/page/288/mode/2up
Glover:
https://archive.org/details/McGillLibrary-hssl_visitation-yorkshire_CS437Y4A2-19990/page/n131/mode/2up
Flowers:
https://archive.org/details/visitationofyork1618flow/page/n247/mode/2up
The fact that John Accom was 19 years old when Ellen was married in 1493 should eliminate the possibility that he was her father and leave Richard as Ellen's probable father.
Another conroversy arises from the Flower pedigree which shows Richard's daughter Ellen as the wife of Thwayts. That would be Marmaduke Thwaites who is shown in other pedigrees as married to another Ellen, the daughter of John Acclom. Little significance should be given to the Flower pedigree, however, as it is followed by the notation: "This pedigree had been seen to be so defective that Ralph Brooke inserted the Visitation of 1585 to correct it."
Therefore, it is most likely that Ellen was the daughter of Richard Acclom. Please provide any further information that may be of relevance.