-Read carefully how they describe the 4th in [square braces]
[[[They use [square braces] for doubt, perhaps, uncertain, flexible]]]
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[m fourthly ([Burgos] 1100 before 14 May) ISABEL [Elisabeth], daughter of --- (-before Mar 1106, bur Royal Pantheon of San Isidor de León). The Chronicon Regum Legionensium names "Elizabeth" as the fourth of the "five legitimate wives" of King Alfonso, stating that she was the mother of "Sancha the wife of count Rodrigo and Elvira who married Duke Roger of Sicily"[508]. According to Reilly, her first documentary mention is dated 14 May 1100, but he does not cite the reference[509]. "Adefonsus…totius Hispanie imperator" donated property to the monastery of San Salvador de Oña with the consent of "uxoris mee Helisabeth regine" by charter dated 12 Dec 1075[510], although this date is clearly incorrect. "Aldefonsus rex Yspaniarum…cum…coniuge mee Helisabeth regine" donated property to the monastery of San Salvador de Oña by charter dated 1086[511], also clearly misdated. "Adefonsus Rex Imperator Ispanie et Regina Elisabeth" protected the grazing rights of Valladolid Santa María by charter dated 1100[512]. "Adefonsus totius Ispanie imperator" donated property to the monastery of San Salvador de Oña with the consent of "uxoris mee Helisabet regine" by charter dated 23 Mar 1103[513]. Her origin is not known. Reilly assumes a French origin, speculating that she belonged to a younger branch of the house of Burgundy, but quotes no documentary evidence for this or any other French origin[514]. It used to be widely accepted that she was the daughter of Louis VI King of France, based on a funerary inscription, but this is chronologically impossible. Her existence is questionable and it is possible that she was in fact the same person as Isabel née Zaïda, shown below as King Alfonso's fifth wife. The question of the separate existence of King Alfonso VI's fourth wife would be resolved if we knew there had been two different memorials to "Queen Elisabeth" in the Royal Pantheon, but it appears that a record of these memorials no longer exists. According to Reilly, she is last named in a charter dated 14 May 1107[515], but it is more likely that this document refers to Queen Isabel/Elisabeth née Zaïda (see below).]
m fifthly (Mar 1106) as her second husband, ZAÏDA, widow of ABU NASIR al Fatah al Ma'Mun Emir of Córdoba, daughter of --- (-13 Sep 1107, bur Royal Pantheon of San Isidor at León). The Chronicon Regum Legionensium names "Zaida, the daughter of King Abenabeth of Seville, who was baptised…Elisabeth" as the second of two concubines of King Alfonso, and their son "Sancho who died at the battle of Ucles"[516]. The Chronicon de Cardeña records that King Alfonso married “Mora, que decien la Cayda, sobrina de Abenafanle” who was mother of his son Sancho[517]. Her first marriage is confirmed by the Bayan al Mugrib of Ibn Idari which names "le fils d´Alphonse, Sancho, qu´il avait eu de l´épouse d´Al Mamun ibn Abbad" when recording the battle of Uclés[518]. Salazar y Acha attempts to explain these three apparently contradictory sources by suggesting that Zaida could have been the daughter of "un hermano mayor…Ismail ibn Abbad" of Mohammed al-Mutamid, noting particularly the practice of endogamous marriages in the Muslim dynasties[519]. As noted above, Ismail is recorded as the brother of al-Mutatid and so would have been the paternal uncle of al-Mutamid. From a chronological point of view therefore Salazar y Acha´s suggestion appears untenible, although Zaida could have been another relative, maybe the daughter of an otherwise unrecorded brother of al-Mutamid. Alberto Montaner Frutos also discusses Zaïda, in particular relating to legends which have developed in connection with her history[520]. Reilly[521] dates the start of her relationship with King Alfonso to late 1091 or 1092, suggesting its diplomatic importance would have been greatest after the fall of Córdoba in Mar 1091 but before the fall of Badajoz in early 1094. This seems supported by the likelihood that their son Sancho was at least 15 years old when he was killed at the battle of Uclés in May 1108. Zaïda was christened ISABEL[522], date not known. Reilly cites a document of Galician origin dated 27 Mar 1106 which indicates that King Alfonso had married "Helisabet" shortly before[523]. Reilly[524] quotes a charter granted at Oviedo 19 Mar 1106 which lists members of the royal family, naming "Elisabeth" directly before "Sancho", which presumably refer to Zaïda and her son. "…Helisabet Regina, Reimundus comes, Urraca regis filia, Sancius filius regis…" subscribed the charter dated 14 May 1107 under which "Adefonsus…Toletani imperii rex…cum…uxore mea Helisabet regina" approved the mint of Santiago de Compostela[525]. Reilly assumes that the reference is to King Alfonso´s presumed fourth wife Isabel (Elizabeth)[526], but it appears more likely that the document refers to Zaïda. Reilly says that her sepulchral inscription (presumably now lost) reportedly stated that she had died in childbirth on 13 Sep, without giving the year, and in a later passage that the inscription stated that this was the "second ferial day", which he interprets as meaning a Monday or Thursday[527]. If the charters dated 1106 and 1107 correctly refer to Zaida, the year must have been 1107 assuming that King Alfonso married his sixth wife in 1108. Pérez´s history of Sahagún monastery, published in 1782, states that Queen Isabel was buried "en la Capilla mayor" of the monastery, but does not quote the inscription which confirms this statement[528].
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& Leave it alone Wiki, look also the MedLands of the 3 children do not mention doubts. (but we didn't spam those here either)
You have to see the presentation of Medlands as an equation developed to show you the solution...