I need a second sister name to go along with [name_u]Simone[/name_u], [name_m]Scott[/name_m] and [name_u]Shane[/name_u].
I really like [name_f]Sienna[/name_f] as a contender but not sure about it. Ideally another S name (accidentally pattern after naming the first two and not wishing the third to stand out with a different letter) so I think the baby might stand out as “different” when she’s older and is the only one without an S name.
Also need to avoid names that end in “er” due to the surname.
One of my favorite S names is [name_f]Sunniva[/name_f] (pronounced soo-neev-a) and it could be an option for you. It has so many great nicknames - [name_f]Sunni[/name_f], [name_f]Neve[/name_f], [name_f]Sue[/name_f], [name_f]Niva[/name_f]. It might stand out a bit against the other names though.
I also like the suggestions of [name_f]Sabine[/name_f], [name_f]Selah[/name_f] and [name_f]Sylvie[/name_f].
I think [name_f]Soleil[/name_f] (so-[name_m]LAY[/name_m]) would be lovely especially with her sister [name_u]Simone[/name_u] as they both have [name_m]French[/name_m] roots.