From a 2018 posting:
EVDOKIA Komnene, daughter of --- ([1160/64]-[Nov 1202/Jun 1204]). The parentage of Evdokia is not known. According to Sturdza[1586], she was the daughter of Alexios Komnenos, son of sébastocrator Andronikos Komnenos (older brother of Emperor Manuel I) but the primary source on which this is based has not yet been identified. Barzos suggests[1587] that she was the daughter of Isaakios Komnenos, son of Emperor Ioannes II, writing that "if Eudokia [K. 143, according to his numbering] were not the daughter of Isaakios [K. 78], then she would be a daughter of Ioannes [K. 128] [son of Andronikos Komnenos sébastocrator]". However, there appear to be too many unknown factors in the genealogy of the Komnenos family for arguments by elimination to be reliable. The Histoire de Montpellier recounts that she travelled to Europe to marry Alfonso II King of Aragon, but found that he was already married to Sancha de Castilla (18 Jan 1174)[1588] when she arrived, that she and her retinue waited for instructions from the emperor at Montpellier, where Guillaume [VIII] proposed marriage to her[1589]. The Annales Pisani (probably written [1182]) records that "l'Imperatore Emanuel" sent his envoys to arrange the betrothal of "una sua nepote…al fratello del Re di Aragona" (Raymond Bérenger III Comte de Provence), the projected marriage aimed at thwarting the influence of the Emperor Friedrich "Barbarossa" through an alliance with Emperor Manuel I, but the betrothal was terminated by Emperor Friedrich as suzerain over the Comté de Provence, the emperor proposing "Goglielmo di Mompellieri" [Guillaume [VIII]] as a suitable alternative[1590]. She became a Benedictine nun at Aniane.
[1586] Sturdza, M. D. (1999) Dictionnaire Historique et Généalogique des Grandes Familles de Grèce, d'Albanie et de Constantinople (2e edition Paris), p. 276.
[1587] Barzos, K. [Genealogy of the Komnenoi], vol. II, p. 14, n. 19 . [J.-C. Chuat]
[1588] Zurita, Ann., 2, 33; Índices/José Guillén Cabañero (1984), tome 1, p. 127. [J.-C. Chuat]
[1589] D'Aigrefeuille Histoire de Montpellier, pp. 67-8.
[1590] Annali Pisani. Continuazione volgara, 1179, pp. 67-8, available at <http://dante.di.unipi.it/ricerca/html/anp.html> (25 Nov 2006).
https://groups.google.com/forum/m/#!topic/soc.genealogy.medieval/XK...
With a preceding comment:
“ The parentage of Eudokia Komnene, the maternal grandmother of King James I of Aragon, ancestor to many of us, is unknown, except that she is a grand-niece of Byzantine Emperor Manuel I Komnenos. Some have proposed that she was the daughter of Isaac Komnenos (son of Emperor John II) and Irene Diplosynadene, but I believe some have pointed out problems with this. Either way, is it safe to presume that Eudokia is either the granddaughter/great-granddaughter of Byzantine Emperor John II Komnenos and Queen Saint Piroska of Hungary?”