I have a Magento website with one store view (ITALIAN) and a theme with the child theme and everything is working good.
Today I created a second store view (ENGLISH) but this doesn't recognize the child theme, but only the default theme.
You must go into System -> Configuration -> Design. Then choose the english store view in top left. Uncheck the use website and insert your package and theme details as you did for the Italian store view. Clear the cache.