Some suggestions (although you should replace 'Ariella' with the correct name for the situation!):
- Instead of I'm sorry about what happened, try I'm sorry about Ariella
- Instead of I'm sorry for your loss, try I'm sorry you lost Ariella
- Instead of Congratulations on giving birth, try Congratulations on birthing Ariella
It's not that the first options are bad, it's just that there is something special about hearing your child's name. After all, it was chosen because the parents loved it. If their child had lived, they'd be hearing it every day for years and years. When their child dies, it means they won't get to say or hear the name as often. If you think they've chosen a beautiful name, tell them! One lady told me that "Ariella Jade" sounded like a song. I loved hearing that. And if you don't like the name...keep that view to yourself (!!), but still use the child's name. Please. The parents will love it.