solution 1(in-depth studies published citing primary sources) & 3(deduction from primary source?) match now; Indeed not among well sourced Amedeo's known daughters /!\

• https://es.wikipedia.org/wiki/Berta_(reina_de_Le%C3%B3n)

1. Según Pelayo, obispo de Oviedo(...-1153) continuando la Crónica de Sampiro, Berta era «natural de Toscana». ​[2][3]
2. /!\ El genealogista Szabolcs de Vajay(1921-2010) opina que fue hija de Amadeo II de Saboya,[4]​
3. mientras que otras fuentes aseguran que en realidad era hija de Guillermo I de Borgoña, conde de Borgoña y Mâcon. [a]

[2] Martínez Díez, 2003, p. 162.
[3] Elorza et al., 1990, p. 55.
[a] En la Crónica General, dice que «don Enrique, el que casó con doña Teresa, hija de Alfonso VI, tuvo a doña Berta como natural de Borgoña». En un diploma datado el XV kalendas noviembre de 1096 en la Colección Diplomática de San Martín de Jubia (977-1199), documento XV, p. 67, consta en la datación «Regnante rex Adefonsus in Toleto et coniuge sua de genere francorum.»

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{Solution 1 & 3 are not contradictory, they match because Guglielmo I "il Grande" conte di Borgogna is Boson d'Arles, margrave of Tuscany's third great grandson! }

Bertha (c. 1070- 1098/1100), wife of Alfonso VI.

"By April 1095, Alfonso married Bertha. Chroniclers report her as being from Tuscany, Lombardy, or alternatively, say she was French. Several theories have been put forward regarding her origin. Based on political considerations, proposals make her daughter of William I, Count of Burgundy or of Amadeus II of Savoy. She had no children and died in late 1099 (Alfonso first appears without her in mid-January 1100)."

• Alfonso VI of León and Castile at Wikipedia, visited Sept. 1, 2013 (of Savoy on 2021)

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• http://fmg.ac/Projects/MedLands/BURGUNDY%20Kingdom.htm#BertheBourgo... (2021)

   Guillaume I & his wife had [thirteen] children: 

13. [ BERTHE de Bourgogne (-early Jan 1100, bur Sahagún, León, royal monastery of Santos Facundo y Primitivo).
-The Chronicon Regum Legionensium names "Berta, who was of Tuscan descent" ("Bertam Tuscia oriundam") as the third of the "five legitimate wives" of King Alfonso[124].
-Las crónicas anónimas de Sahagún refer to her as "otra mugger de la nacion de Lombardia llamada Berta". [ another woman from the nation of Lombardy named Berta - SHARON 2025]
The precise origin of Berthe is not known.
-According to Europäische Stammtafeln[125], she was the daughter of Guillaume I Comte [Palatin] de Bourgogne, Comte de Vienne et de Macon, which is inconsistent with the "Tuscan descent" reported in the Chronicon Regum Legionensium.
-Szabolcs de Vajay suggests that she was the daughter of Guillaume Comte de Bourgogne[126].
-Reilly does not mention this possible Burgundian origin of Berthe, implying that the Castilian king chose his third wife from outside the Burgundian circle in order to diminish the influence of the Burgundians at court. As Berthe de Bourgogne would have been the sister of Raymond de Bourgogne who married Infanta doña Urraca, oldest legitimate daughter of King Alfonso, around the same time that King Alfonso married Queen Berta, it is surprising that the chronicles do not refer to this relationship if it is correct.
-The references to "Tuscia" and "Lombardia" in the chronicles could be consistent with the family of Bourgogne [Comte] having originated in northern Italy, their ancestors being Marchesi of Ivrea until 968, although this was nearly 130 years before the date of Queen Berta's marriage.

Reilly dates this marriage to "during the Christmas season of 1094", but does not state his source[127]. In a later passage, Reilly states that the first reference to Berta as queen is dated 28 Apr 1095 [128]. According to Reilly, Queen Berta died shortly after the new year 1100, probably before 16 Jan[129]. In another passage, he notes that the last notice of her is dated 17 Nov 1099 [130]. She was dead in 25 Jan 1100, the date of the charter under which "Adefonsus…Toletani imperii rex" donated the churches of "Sancti Facundi et Sancti Primitivi…cum sua villa…Villaverde", ceded by "comitis Monini Fernandis…in vita sua dederam uxori mee Berte regine", to Cluny, confirmed by "Raimundus totius Gallecie comes et gener regis, Urraca soror regis, Urraca regis filia et Raimundi comitis uxor, Enricus Portugalensis comes, uxor ipsius Tarasia filia regis…"[131].

m ([Dec] 1094) as his fourth wife, ALFONSO VI King of Castile and Leon, son of FERNANDO I "el Magno" King of Castile and León & his wife doña Sancha de León (Compostela [1037]-Toledo 30 Jun 1109, bur Sahagún, León, San Mancio chapel in the royal monastery of Santos Facundo y Primitivo).]

Reilly's thesis:

Ch 14 of The Kingdom of León-Castilla Under King Alfonso VI by Bernard F. Reilly

His mentions of Berta are in Ch 14 of The Kingdom of León-Castilla Under King Alfonso VI
Bernard F. Reilly - as follows

It is possible as well that the very rapid remarriage of the Aragonese king in 1097 reflected his continuing need for the kind of prestige a wife of foreign extraction could give. His wife Agnes of Poitou was last mentioned in a charter of May 9, and his marriage to a new wife took place on August 16, 1097, in the cathedral of Huesca.(6)[284] Curiously enough, his bride too was of Italian origin and bore the name of Berta....

Sometime early in May the king left León to initiate a military campaign. On May 19, 1097, he granted a charter of immunity to the Castilian monastery of Silos. He was then in the tiny village of La Aguilera a few kilometers northwest of Aranda de Duero.(13) The confirmations give us a good look at the composition of a royal army actually on campaign. Queen Berta was there as was Infanta Urraca and her husband Count Raymond...

At least in some quarters the celebrations of the Christmas season would have become somber soon enough for Alfonso's third queen, Berta, died shortly after the new year. She was probably already deceased when Alfonso, in León, issued a charter to the church of Santiago de Compostela on January 16, 1100. A week later at Castrofruela the charter that Alfonso granted to Sahagún commemorated [296] her memory.(60) This latter charter reveals the presence of the king's sister, Urraca, and his two daughters, Urraca and Teresa, together with the husbands of the latter two, the counts Raymond and Henry. The first thoughts of all would already have turned to the choice of a new wife for the king. Given the speed with which he was provided with one the choice must have been made then and an embassy dispatched to summon his bride. It also seems obvious that Queen Berta had been seriously ill for some time and that previous, polite inquiries had been made. Otherwise the entire sequence of events is simply incredible.

Wikipedia

Berta de Toscana

http://es.wikipedia.org/wiki/Berta_de_Toscana

Berta de Toscana (fallecida el 25 de enero de 1100). Reina consorte de León por su matrimonio con Alfonso VI el Bravo. Aunque se desconoce su genealogía, se cree que fue hija del duque de Toscana, aunque ciertas fuentes aseguran que en realidad era hija de Guillermo I de Borgoña, conde de Borgoña y Mâcon.

Contrajo matrimonio en el año 1094 con Alfonso VI el Bravo, rey de León, quien había enviudado en 1093 de su segunda esposa, Constanza de Borgoña.

La reina Berta de Borgoña, que falleció sin haber dado hijos al rey Alfonso VI, murió el día 25 de enero de 1100.

Después de su defunción, el cadáver de la reina Berta de Toscana fue conducido a la localidad leonesa de Sahagún y sepultado en el Monasterio de San Benito de Sahagún, donde su esposo, el rey Alfonso VI el Bravo, recibiría sepultura posteriormente, en compañía de algunas de sus esposas.

Fachada del Monasterio de Benedictinas de Sahagún, donde yacen los restos de la reina Berta de Toscana.

El sepulcro que contenía los restos de Alfonso VI fue destruido en 1810, durante el incendio que sufrió el Monasterio de San Benito. Los restos mortales del rey y los de varias de sus esposas, entre ellos los de la reina Berta de Toscana, fueron recogidos y conservados en la cámara abacial hasta el año 1821, en que fueron expulsados los religiosos del monasterio, siendo entonces depositados por el abad Ramón Alegrías en una caja, que fue colocada en el muro meridional de la capilla del Crucifijo, hasta que, en enero de 1835, los restos fueron recogidos de nuevo e introducidos en otra caja, siendo llevados al archivo, donde se hallaban en esos momentos los despojos de las esposas del soberano. El propósito era colocar todos los restos reales en un nuevo santuario que se estaba construyendo entonces.4 No obstante, cuando el monasterio de San Benito fue desamortizado en 1835, los religiosos entregaron las dos cajas con los restos reales a un pariente de un religioso, que las ocultó, hasta que en el año 1902 fueron halladas por el catedrático del Instituto de Zamora Rodrigo Fernández Núñez.4

En la actualidad, los restos mortales de Alfonso VI el Bravo reposan en el Monasterio de Benedictinas de Sahagún, a los pies del templo, en un arca de piedra lisa y con cubierta de mármol moderna, y en un sepulcro cercano, igualmente liso, yacen los restos de varias de las esposas del rey, entre ellos los de la reina Berta de Toscana.

Intrinsiek tegenstrijdige bronnen: https://gw.geneanet.org/fabibon?n=persijn+van+velzen&oc=&p=dirck+jansz

• https://gw.geneanet.org/marierose16?lang=en&iz=13&p=lady+berthe+van... d.[19/5/1098 - 25/1/1100]?? ??
• https://www.genealogieonline.nl/stamboom-van-elderen-en-van-der-spe...
• https://genealogieflakkee.nl/stamboom2/index.php?a=person/4/i_I3268...ë