Out of my list which are your favorites for a sister to [name_f]Margot[/name_f]?
[name_f]Audrey[/name_f] - I really like but don’t love
[name_f]Colette[/name_f] - is it too fancy?
[name_f]Cora[/name_f]
[name_f]Gemma[/name_f]
[name_f]Lyla[/name_f]
[name_f]Lola[/name_f]
[name_f]Serena[/name_f]
[name_f]Stella[/name_f] - too popular?
[name_f]Tess[/name_f]
I love:
[name_f]Margot[/name_f] and [name_f]Audrey[/name_f]
[name_f]Margot[/name_f] and [name_f]Cora[/name_f]
[name_f]Margot[/name_f] and [name_f]Colette[/name_f]
[name_f]My[/name_f] personal fave on your list is [name_f]Tess[/name_f] but I think the best matches with [name_f]Margot[/name_f] are [name_f]Audrey[/name_f] and [name_f]Stella[/name_f] followed by [name_f]Colette[/name_f], [name_f]Gemma[/name_f], and [name_f]Serena[/name_f].
[name_f]Tess[/name_f] is my favourite today!
The [name_f]Margot[/name_f] I know has a sister named [name_f]Noelle[/name_f]! (I’ve also met another with three sisters: [name_f]Claire[/name_f], [name_f]Elise[/name_f], and something I can’t remember.)
I think your list goes lovely with [name_f]Margot[/name_f]. Especially I like [name_f]Colette[/name_f], [name_f]Cora[/name_f], and [name_f]Gemma[/name_f]!
Ideas to add:
[name_f]Emmeline[/name_f]
[name_f]Louise[/name_f]
[name_f]Beatrice[/name_f]
[name_f]June[/name_f]
[name_f]Lucy[/name_f]
[name_f]Penelope[/name_f]
[name_f]Elise[/name_f]
[name_f]Georgia[/name_f]
[name_f]Ivy[/name_f]
[name_f]Pippa[/name_f]
[name_f]Willa[/name_f]
[name_f]Vera[/name_f]
With [name_f]Margot[/name_f], I really like [name_f]Colette[/name_f] and [name_f]Cora[/name_f]!
I love [name_f]Margot[/name_f] and [name_f]Tess[/name_f] (Tess is such underrated name!)
Also 
[name_f]Margot[/name_f] and [name_f]Colette[/name_f], [name_f]Margot[/name_f] and [name_f]Audrey[/name_f] and [name_f]Margot[/name_f] and [name_f]Stella[/name_f].
I think [name_f]Collette[/name_f], [name_f]Lyla[/name_f] and [name_f]Tess[/name_f] go great
[name_f]Colette[/name_f], [name_f]Serena[/name_f] and [name_f]Gemma[/name_f] 
[name_f]Margot[/name_f] & [name_f]Lola[/name_f] 
[name_f]Audrey[/name_f], [name_f]Cora[/name_f], & [name_f]Lola[/name_f] seem the most cohesive with [name_f]Margot[/name_f].
When I see something with a T in it with [name_f]Margot[/name_f] (like [name_f]Stella[/name_f] or Tess), it makes me want to pronounce the T in [name_f]Margot[/name_f]. I know that’s not the most common pronunciation of [name_f]Margot[/name_f] (though there are cases where people do pronounce it), but seeing it written with other strong T names would trip me up and make me question.
[name_f]My[/name_f] top three would be
[name_f]Margot[/name_f] & [name_f]Colette[/name_f] - I love the [name_f]French[/name_f] connection between these names
[name_f]Margot[/name_f] & [name_f]Tess[/name_f] - I am completely smitten with [name_f]Tess[/name_f] !
[name_f]Margot[/name_f] & [name_f]Gemma[/name_f] - I feel like [name_f]Gemma[/name_f] is an unexpected “Jem” , it’s simple , not common but complimentary to [name_f]Margot[/name_f]
I think my favourites from your list would be [name_f]Audrey[/name_f], [name_f]Serena[/name_f], [name_f]Stella[/name_f] and Gemma!!
Margot & Tess (so pretty!)
Margot & Gemma (super vibrant)
Margot & Audrey (but you don’t seem keen so I would sub in Serena)
I don’t think Colette is too fancy, but I’ve just only met very pallid Colettes and I don’t love the sound. There are more beautiful French names out there (eg Leonore, Adelaide, Fleur - and I like Cosette nn Cosy better than Colette).
I think Lyla and Lola will get a little lost against the more robust Margot. I anyway prefer them as nicknames - eg Delilah nn Lila or Penelope/Eloise nn Lola - they all go with Margot.
Other ideas:
Margot & Phoebe
Margot & Zara
Margot & Diana
Margot & Willa
Margot & Hazel
Hope that helps!
[name_f]Audrey[/name_f]! (also love Tess)
[name_m]Hi[/name_m] there.
Here are my favorite to least favorite rakings:
Tess-This is my favorite in general & with [name_f]Margot[/name_f]! It’s just a little spunky, a little sporty but just the right touch of sweet and feminine. It’s vintage but feels fresh. It’s kind of nick-name-y, but good enough for a full name. All of the same qualities [name_f]Margot[/name_f] has.
Stella-This is my second favorite on the list & also it’s great with [name_f]Margot[/name_f]. It is kind of popular though if that bothers you. All things ‘elle’ are popular, you know? I do love the glamour vibe of [name_f]Stella[/name_f].
Gemma-This is so pretty & simple & soft with just the right amount of flair. Similar in sound to [name_f]Stella[/name_f] but less common.
Colette-Nah, it’s not too fancy! I like it a lot. It’s just the right amount of fancy. It’s fairly well known but not at all popular.
Cora-I like it, but I really dislike Cori…which may or may not be avoidable. [name_f]Cora[/name_f] is old fashioned & has simple homey charm. Maybe it just doesn’t sparkle as much as some of the others.
Lola-I like this a lot, & it has the right vibe…I just really want it to be a nn. I like [name_f]Louisa[/name_f], [name_f]Eloisa[/name_f] or [name_f]Lorelei[/name_f] nn [name_f]Lola[/name_f].
Audrey-Hm. I actually like [name_f]Audrey[/name_f] more than [name_f]Lola[/name_f] & Cora…but I think it’s maybe too rhyme-y with [name_f]Margot[/name_f]?
Lyla-I may have made this higher on the list if it were [name_f]Lila[/name_f]. Not a fan of the ‘y’.
Serena-It’s not an unpleasant name, just feels a little modern for my taste. Doesn’t fit the style of [name_f]Margot[/name_f] that well.
[name_f]Hope[/name_f] this helps. 
[name_f]Margot[/name_f] & [name_f]Cordelia[/name_f]
[name_f]Margot[/name_f] & [name_f]Cecily[/name_f]
[name_f]Margot[/name_f] & [name_f]Majorie[/name_f]
[name_f]Margot[/name_f] & [name_f]Melanie[/name_f]
[name_f]Margot[/name_f] & [name_f]Madelyn[/name_f]
[name_f]Margot[/name_f] & [name_f]Gracie[/name_f]
[name_f]Margot[/name_f] & [name_f]Sophie[/name_f]
[name_f]Margot[/name_f] & [name_f]Lizbeth[/name_f] “lizzie”
[name_f]Margot[/name_f] & [name_f]Aurora[/name_f]
[name_f]Margot[/name_f] & [name_f]Elaine[/name_f]
[name_f]Margot[/name_f] & [name_f]Brielle[/name_f]
[name_f]Margot[/name_f] & [name_f]Camille[/name_f]
[name_f]Margot[/name_f] & [name_f]Hallie[/name_f]
[name_f]Margot[/name_f] & [name_f]Vanessa[/name_f]
[name_f]Margot[/name_f] & [name_f]Ianthe[/name_f]
[name_f]Margot[/name_f] & [name_f]Valerie[/name_f]
[name_f]Margot[/name_f] & [name_f]Maisie[/name_f]
[name_f]Margot[/name_f] & Hollynd
[name_f]Margot[/name_f] & [name_f]Melinda[/name_f]
[name_f]Margot[/name_f] & Nesta/ [name_f]Nessa[/name_f]