Congratulations on girly number 2! Her birth must’ve been terrifying–it sounds like she’s okay? [name_f]Praise[/name_f] the [name_m]Lord[/name_m]!
My first idea was [name_f]Adele[/name_f], and I think [name_f]Adele[/name_f] [name_u]Ruby[/name_u], [name_f]Adele[/name_f] [name_f]Matilda[/name_f] (to get that great meaning!) or [name_f]Adele[/name_f] [name_f]Ethelyn[/name_f] would all be lovely. Or [name_f]Adele[/name_f] [name_f]Margaret[/name_f]? I’m obviously biased, though, as [name_f]Grace[/name_f] and [name_f]Adele[/name_f] sit right next to each other on my list, and so it probably just came second nature. 
I, myself, imagine a future [name_f]Adele[/name_f] I might have to be a light-haired beauty, so it just seemed perfect! And [name_f]Addy[/name_f] and [name_f]Della[/name_f] are so cute.
Of your options, I like [name_f]Margaret[/name_f] the best–I think [name_f]Maggie[/name_f], [name_f]Daisy[/name_f], [name_f]Greta[/name_f], [name_f]May[/name_f], or [name_f]Maisie[/name_f] could all fit a light-haired beauty, but don’t necessarily have to, although [name_f]Margaret[/name_f] [name_f]Ethelyn[/name_f] seems a bit too old-fashioned for me still. 
[name_f]Matilda[/name_f]'s not my cup of tea, but [name_f]Tilly[/name_f] is so adorable. [name_u]Ruby[/name_u]'s cute, but I can’t imagine it on a light-haired little girl. Probably just me, though. 
[name_f]Margot[/name_f]'s spunky and cool, but again, I’m not too keen on [name_f]Margot[/name_f] [name_f]Ethelyn[/name_f]. [name_f]Margot[/name_f] [name_u]Ruby[/name_u] or [name_f]Adele[/name_f] [name_f]Margot[/name_f] (omgoodness, I am obsessed, lol) would be sweet, though! I especially love [name_f]Adele[/name_f] [name_f]Margot[/name_f]. She seems very [name_m]German[/name_m]/[name_m]French[/name_m] chic to me, although I have no clue if either of those names are either popular, chic, or even used in either of those countries.
A few other ideas:
[name_f]Grace[/name_f] and [name_f]Olive[/name_f]
[name_f]Grace[/name_f] and [name_f]Audrey[/name_f] ([name_f]Audrey[/name_f] means “noble strength”, which I think is fantastic, and could be totally fitting in this case!)
[name_f]Grace[/name_f] and [name_f]Penelope[/name_f]
[name_f]Grace[/name_f] and [name_f]Julia[/name_f]
[name_f]Grace[/name_f] and [name_f]Amelia[/name_f] (echoing this one!)
[name_f]Grace[/name_f] and [name_f]Charlotte[/name_f]
[name_f]Grace[/name_f] and [name_u]Eloise[/name_u]
[name_f]Grace[/name_f] and [name_f]Elora[/name_f] (love this one! Not sure if you’re religious/[name_m]Christian[/name_m] or not, but if you are, it means “the [name_m]Lord[/name_m] is my light” (or something similar?), which could be meaningful in this case?)
[name_f]Grace[/name_f] and [name_f]Eleanor[/name_f]
[name_f]Grace[/name_f] and [name_f]Sofia[/name_f]
[name_f]Grace[/name_f] and [name_f]Noemi[/name_f]
[name_f]Grace[/name_f] and [name_f]Zoe[/name_f] (“life”)
[name_f]Grace[/name_f] and [name_f]Eva[/name_f]/[name_f]Eve[/name_f] (“life”)
[name_f]Grace[/name_f] and [name_f]Noelle[/name_f]
[name_f]Grace[/name_f] and [name_f]Magdalena[/name_f]
[name_f]Grace[/name_f] and [name_f]Thea[/name_f]
[name_f]Grace[/name_f] and [name_f]Tessa[/name_f]
[name_f]Grace[/name_f] and [name_f]Violet[/name_f]
[name_f]Grace[/name_f] and [name_f]Felicity[/name_f] (too themey for sisters?)
[name_f]Grace[/name_f] and [name_f]Delphine[/name_f]
[name_f]Grace[/name_f] and [name_f]Adelia[/name_f] (could use [name_f]Della[/name_f] or [name_f]Delia[/name_f] as a nn for this, if you like?)
[name_f]Grace[/name_f] and [name_f]Isabelle[/name_f]
[name_f]Grace[/name_f] and [name_f]Arielle[/name_f]/[name_f]Ariella[/name_f]
[name_f]Grace[/name_f] and [name_f]Aurora[/name_f]
[name_f]Grace[/name_f] and [name_f]Claire[/name_f] (love this one, too!)
[name_f]Grace[/name_f] and [name_u]Eden[/name_u]
[name_f]Grace[/name_f] and [name_f]Beatrix[/name_f]
[name_f]Grace[/name_f] and [name_f]Bianca[/name_f]
[name_f]Grace[/name_f] and [name_f]Nadia[/name_f] (means “hope”)
[name_f]Grace[/name_f] and [name_f]Helena[/name_f]
Good luck!