[name_f]Marigold[/name_f] was my first thought to fit the criteria too!
I think [name_f]Genevieve[/name_f] would be lovely with the sibling names as well.
For unusual floral names, maybe [name_f]Acantha[/name_f], [name_f]Betony[/name_f], [name_f]Iolanthe[/name_f], [name_f]Rosemary[/name_f], [name_f]Fenella[/name_f], [name_f]Daylily[/name_f], [name_f]Olivet[/name_f], [name_f]Marjolaine[/name_f].