The Overview for her father points you to some of the sources:
Withur d'Acqs, count of Léon (Parzival)
Justin Durand -- I haven't got a copy of Parzival to hand; have you got one?
Ither the Red Knight is clearly fictional, but Osoche is showing up in sources that may be reliable. What I can't tell is if Ither is given a son in the poem, or if Osoche has been given a fictional father in the genealogies.
I do have a copy of Parzival here but it's not indexed. I'll have to find a read the relevant passages.
The glossary doesn't mention children. It says:
> Ither of Gaheviez. King of Cucumerlant; Utepandragun's maternal nephew; husband or lover of Lammire; related to Parzival by blood only through his grandfather (Parzival's great-great-great-grandfather) Mazadan, though Gahmuret claims him as 'maternal kinsman'; 'the Red Knight' until Parzival slays him."
I've now snuck a few minutes to read the chapter. Nothing more there. In fact, not as much there as in the glossary.
I wonder if this little piece will come through on a web link:
https://books.google.com/books?id=IJfhERmwDbUC&pg=PA206&lpg...
I'm guessing the connection to Osoche will be somewhere in the Holy Blood, Holy Grail materials. I'll check when I get time.
In Laurence Gardner, Bloodline of the Holy Grail: The hidden lineage of Jesus revealed (1996), p. 185, we see:
Ywain "Founder of the House of Leon d'Acqs c.530" son of King Urien of Rheged and father of Withur "Comte de Leon d'Acqs". Withur is father of Ausoch, also Comte de Leon d'Acqs, who Ausoch is father of Pritelle, who married Hoel III, King of the Bretons.
You see the silliness. This was the line on Geni that got broken up. Totally at odds even with the medieval romance of Parzival.
It would be better to start with something like EBK, which says "LÉON, if it ever really existed, flourished in the 6th century. Men named Withur and Ausoch may have been two of its sovereigns."
http://www.earlybritishkingdoms.com/articles/bretart.html
You mean a Holy Blood, Holy Grail line? I don't think so. I was always going to start one, but haven't done it yet.
There's no rush, but we should probably in the end have at least three versions here -- (a) a disconnected line taken from primary documents, (b) a Parzival line for the literary tradition, and (c) a Holy Blood line for the pop history.