Is Henriette's twin brother called..

[GlitterGlass]

Camille, Marcel or Émile?

Camille will be assumed to be a girl in the UK (and I've only met female Camille's in France too).

I'd avoid Emile for the 'Henry ate...' reason. Not overly keen on Marcel but it's the best of the three. How about Clement, Victor, Alexandre, Valentin, Gustave, Olivier?