Alexandra is already a godmother - to her firstborn nephew Prince Gabriel (son of Prince Louis).
Good that other family members got this chance! (especially giving the fact that both Guillaume and Stephanie come from big families and there are many candidates to be godparents).
For another sibling's kids. Not same as Guillaume chosing
I dont expect Claire.They seem to stick to actual siblings not in law
Henri's grandkids:
-Gabriel: Alexandra (paternal) Ronny Antony (Maternal)
-Noah: Guillaume (paternal) Patty Antony (maternal)
-Amelia: Alexandra (paternal) Felix Lademacher (maternal)
-Liam:Sebastian (paternal) Anna-Maria Pamin (friend)
-Charles: Louis (paternal) Gaelle de Lannoy (maternal)
Felix is the only sibling not yet chosen. Maybe with one of Stephanie's sisters.
Henri's kids similar for first 3, then ran out of siblings:
-Guillaume: Marie Astrid and Guillaume (2 of his dad's siblings)
-Felix: Prince Jean (paternal) Catalina Mestre (maternal)
-Louis: Princess Margaretha (paternal) Xavier Sanz (friend)
-Alexandra: Archduchess Maria Anna of Austria and Prince Michael de Ligne
-Sebastian: his brother Guillaume and Princess Astrid of Belgium