thank you 
i love [name_f]Sylvie[/name_f] too, and agree she fits very well. dh’s great grandfather was [name_m]Sylvester[/name_m] too, which makes her even sweeter— [name_f]Sylvie[/name_f] [name_f]Hosanna[/name_f] would actually be really sweet! 
i agree with your point on [name_f]Fern[/name_f]— it does feel like a [name_f]Florence[/name_f] nickname, and though she was once our front runner, i think a double rainbow baby might need something a bit more special, if that makes sense! 
i love your idea of [name_f]Oona[/name_f] & [name_f]Leonie[/name_f]. i actually had a great great grandma called [name_f]Leonie[/name_f], and i love the nickname “Leo”. [name_f]Primrose[/name_f] “Posie” is also great 