I commented on this name a while ago and I’m not in the mood to make an original comment, so I’ll just copy-paste what I wrote:
I do like
Isabeau! It has an elegantly medieval charm - and would be a breath of fresh air from the hundreds of Isabellas running around right now.
I would name a brother and sister something similarly medieval: maybe Edmund/Everard &
Amabel?
Sylvain & Rosceline for something more French?