[name]Isobel[/name] [name]Sarah[/name]! [name]Isabelle[/name] [name]Sarah[/name] is on our list for possible fn with [name]Sarah[/name] as a mn. I like [name]Isabel[/name]/[name]Isabelle[/name], but [name]Isobel[/name] is pretty as well.
I think both would go nicely with [name]Sarah[/name]! [name]Isabella[/name] (and variants) is definitely rather popular, but if you love the name, it shouldn’t matter 
Personally, I like the sound of [name]Imogen[/name] [name]Sarah[/name], and there was an article on nameberry about the nickname Idgie being used for a little [name]Imogen[/name]. I just think it’s totally adorable. I love nicknames and names that have many nickname options, so hearing that one made me fall for [name]Imogen[/name], haha.