Don't know how valid any of these are, but I thought I'd pass it on to you.
http://homepages.rpi.edu/~holmes/Hobbies/Genealogy2/ps04/ps04_307.htm
http://www.cft-win.com/getperson.php?personID=I011267&tree=Norway
https://books.google.com/books?id=1taIF_hPgd8C&pg=PA25-IA21&...
No clear answer. MedLands places him as son of Arnoul based on a theory he might have been the Walacho who is recorded as son of Bishop Arnoul (died 640), but if he was father-in-law of Eudes of Aquitaine (died 735) then the chronology is too extended.
http://fmg.ac/Projects/MedLands/FRANKSMaiordomi.htm#_Toc359686215
I keep Walchisus / Walchigise and Walacho separate in my notes, with an unsourced wife Waldrada / Valtrude, and a note Walchisus might have been a son of Arnoul if he was the same person as Walacho.
In this year 1738 book, Arnoult has two children, Walchise and Clodukphe
https://books.google.fr/books?id=XjNw5prownQC&pg=PA89&lpg=P...
Clodulphe was a servant for Sigisbert the king and then became Eveque de Metz in year 662 at the age of 46. He died after governing the church for 40 years. He was buried in the church of the saint apostles in Metz. He has a wife and a son called Martin. But Ebroin, Mayor of the palace had Martin killed.
Medlands is giving the primary sources it has available- the discussion needs to be about where we want to go with the compromise of what is not ultimately definitively provable with the primary source data we have.
If nobody was objecting to leaving him here - and it didn't seem to me that you were - then it seemed a reasonable place to leave it as is.
Are you saying you want to move him? - forgive me if I'm missing that. I thought I was adding a source that agreed with you.