i can only make the chronology fit with her mother being daughter of Ragnall / Ranald / Reginald of the Isles by his wife Fonia / Fionnghuala, and the first de Lacy marriage can only have gone ahead after the first two daughters were born. in fact we only know the name of Helen, and her mother is only known as "Helen" since Hilda is shortened form of Ragnhildur and this one is already accounted for.
also noting here that the tree is a jumbled mess out from "Alice de Lacy" where it is mangled and all wrong, so good luck and fortitude to anybody who goes to work on putting that section right.
ALAN of Galloway, son of ROLAND Lord of Galloway & his wife Helen de Moreville (-[2] Feb 1234, bur Dundraynan[1178]). ...
m firstly (before [19 Dec 1200/1206]) --- de Lacy, daughter of ROGER de Lacy Constable of Chester & his wife Matilda de Clare (-[1201/06]). ...
[m [secondly] --- [of the Isles, daughter of REGINALD Lord of the Isles & his wife Fonie ---] (-before 1209). Balfour Paul says that Alan Lord of Galloway married first "a lady unknown, said to be a daughter of Reginald Lord of the Isles by whom he had two daughters"[1189]. He cites Chalmers’s Caledonia, but that says only that “the name of the first [wife] is unknown” without providing any indication of her family origin[1190]. Balfour Paul repeats his suggestion under the Lords of the Isles where he notes a daughter of Reginald Lord of the Isles "said to have married Alan of Galloway", without citing any source[1191]. There is no indication of the basis for Balfour Paul’s statements and no primary source which confirms this person’s parentage and marriage has been identified. Her existence should presumably be treated with caution until some such source emerges. If she did marry Alan, she was not the mother of his daughter Ellen shown below. She was either married before his marriage to “--- de Lacy” or before he married Margaret of Huntingdon: she is shown here, for presentational purposes only, as Alan’s possible second wife.]
Lord Alan & his first wife had two children:
1. ELLEN of Galloway ([before 1205]-after 21 Nov 1245, bur Brackley). The Annales Londonienses name "Eleyn countesse de Wynton" as eldest of the three daughters of "la primere fille Davi" and "Aleyn de Gavei", naming "Margarete countesse de Ferreres et Eleyne la Zusche et la countesse de Bougham" as her three daughters[1202]. It is assumed that she was not born from Alan’s marriage to Margaret of Huntingdon as her descendants did not raise a claim to the Scottish throne in 1291. This is consistent with the date of marriage of one of her daughters being estimated to [1238]. The identity of Ellen’s mother as her father’s first wife is confirmed by her husband Roger de Quincy holding Kippax (linked to Alan’s first wife as shown above)[1203]. Ellen’s birth and marriage dates are estimated from her daughter who married in [1238] having given birth soon after that marriage. The Liber Pluscardensis records that the eldest daughter of "Alanus de Galway filius Rotholandi de Galway" married "Rogerus de Quinci comes Wintoniæ"[1204]. "Elena quondam filia Alani de Galeweya" donated "villam de Edeluestune" to the church of Glasgow by undated charter[1205]. "Rogerus de Quency constabularius Scocie et Elena uxor eius filia quondam Alani de Galweya" recognised the rights of the church of Glasgow to "villam de Edeluestune" by undated charter[1206]. m ([before 1223]) as his first wife, ROGER de Quincy Earl of Winchester, son of SAHER de Quincy Earl of Winchester & Margaret of Leicester (-25 Apr 1264, maybe bur Brackley). He is named son-in-law of Alan of Galloway by Matthew Paris, who does not name his wife[1207] but says in a later passage that she was "primogenita soror"[1208]. He succeeded his father-in-law in 1234 as hereditary Constable of Scotland, de iure uxoris.
Lord Alan & his [first/second] wife had one child:
2. daughter (-before 13 Jun 1213). Balfour Paul says that a daughter of Alan Lord of Galloway by his marriage to "a lady unknown, said to be a daughter of Reginald Lord of the Isles by whom he had two daughters", shown above as Alan’s possible second wife, died "a hostage in charge of Robert FitzRoger shortly before 13 June 1213"[1209]. Whatever the truth about Alan’s marriage to the supposed daughter of the Lord of the Isles, the mother of the older of the two daughters mentioned by Balfour Paul must have been Alan’s first wife as shown above. It is not known whether Balfour Paul mistook the mother of both of these daughters, or whether the second daughter was born to his possible second wife. No primary source has been identified which confirms the existence of this person, although the date quoted by Balfour Paul does suggest the existence of a primary source. http://fmg.ac/Projects/MedLands/SCOTTISH%20NOBILITY.htm#HelenGallow...