[name_m]Hi[/name_m] there, I’ve just signed up looking for advice on baby number four who is due in a few weeks.
We are having a girl and we are torn between three names:
-[name_f]Sylvie[/name_f]
-[name_u]Sunny[/name_u]
-[name_f]Luna[/name_f]
We have three kids already and their names are [name_m]Jasper[/name_m] (9) [name_f]Pearl[/name_f] (5) and [name_m]Felix[/name_m] (2)
What name goes best with the lot and why? We love [name_f]Luna[/name_f] but worry it’s too popular?
TIA
[name_f]Welcome[/name_f] @AnnieAreYouOkay! (Great name 
)
I really love your children’s names, and all the names you’re considering, actually!
Personally, I’d rank your choices for #4 in the order you’ve written them here:
[name_f]Sylvie[/name_f] is sweet and quirky, but also feels traditional, in an unexpected kind of way. It fits perfectly with the cool, chic, retro vibe I get from [name_m]Jasper[/name_m], [name_f]Pearl[/name_f] and [name_m]Felix[/name_m].
[name_u]Sunny[/name_u] is sweet and fun, but has a lot of personality too. I think the nature aspect of it is a nice subtle tie to [name_m]Jasper[/name_m] and [name_f]Pearl[/name_f], and it also reflects [name_m]Felix[/name_m]’s happy meaning. [name_f]My[/name_f] only concern would be that it could sound a little juvenile, especially for a youngest sibling.
[name_f]Luna[/name_f] is such a pretty name, and it has the nature side to recommend it too, but yes: it is becoming increasingly popular, and very quickly too. It feels like more of a flash trend than your other names, which are cool and on the rise, but not too overexposed.
I think @katinka is bang on with her order and her comments. [name_u]Love[/name_u] [name_f]Sylvie[/name_f] for you, especially with [name_m]Jasper[/name_m], [name_f]Pearl[/name_f] and [name_m]Felix[/name_m]. Sibset envy! 
Your kids have great names! [name_f]My[/name_f] favourites are [name_f]Sylvie[/name_f] and [name_u]Sunny[/name_u], although [name_f]Luna[/name_f] is lovely too (but yes, quite popular). With [name_m]Jasper[/name_m], [name_f]Pearl[/name_f], and [name_m]Felix[/name_m] I think my favourite is [name_f]Sylvie[/name_f] but honestly, I could just as easily have said [name_u]Sunny[/name_u], which is so sweet. [name_m]Just[/name_m] an idea - have you thought about [name_f]Sunday[/name_f] nn [name_u]Sunny[/name_u]? That would also be gorgeous with your kids’ names!
EDIT: it’s interesting to see that others have already put your choices in this order - I hadn’t read the previous comments before I responded.
I think [name_f]Luna[/name_f] or [name_f]Sylvie[/name_f] would be perfect with your sibset, and I do like [name_u]Sunny[/name_u] but it sounds a bit like a nickname. I don’t think [name_f]Luna[/name_f] is too popular, but if you know of a lot then I understand not wanting to use it (although I actually know two kids called [name_f]Sylvie[/name_f] and none called [name_f]Luna[/name_f]!)
Wow, I love your taste in names! [name_f]My[/name_f] favourite for you is [name_f]Sylvie[/name_f]. It’s chic and familiar, but not too popular just like your other kids’ names. It’s beautiful!
I like [name_u]Sunny[/name_u] and [name_f]Luna[/name_f] too, but [name_u]Sunny[/name_u] is more of a nickname for me. I think [name_m]Jasper[/name_m] and [name_f]Luna[/name_f] would go well together (both trendy nature names) but with [name_f]Pearl[/name_f] and [name_m]Felix[/name_m], the vibe of the sibset is different if you get what I mean?
I love your options and any one of them will be a great addition to your sibset.
I agree with @katinka’s assessment of the names, but I personally would choose [name_u]Sunny[/name_u], then [name_f]Sylvie[/name_f], then [name_f]Luna[/name_f]. I think [name_f]Sylvie[/name_f] is the best stylistic fit, but [name_u]Sunny[/name_u] would be too good for me to pass up if I had the chance to use it (my partner has vetoed it). Only you can decide though.
I love [name_u]Sunny[/name_u]!
I thnk all the names you are considering are gorgeous! If you want, [name_f]Luna[/name_f] could be a middle? [name_f]Sylvie[/name_f] [name_f]Luna[/name_f] or even [name_u]Sunny[/name_u] [name_f]Luna[/name_f] would sound absolutely gorgeous!
Wow! What a beautiful sibset! 
I like [name_f]Sylvie[/name_f] or [name_f]Luna[/name_f] best. I don’t feel like [name_u]Sunny[/name_u] fits quite as well.
I think my favorite would be [name_f]Sylvie[/name_f]. [name_f]Luna[/name_f] is pretty but it highlights the subtle nature theme of [name_m]Jasper[/name_m] and [name_f]Pearl[/name_f] and I feel like it kind of leaves [name_m]Felix[/name_m] out. Although I do think it’s sounds great with [name_m]Felix[/name_m] too. Hmm tough choice. 
I think I’m still gonna go with [name_f]Sylvie[/name_f].
I second the idea of [name_f]Sylvie[/name_f] [name_f]Luna[/name_f]!
[name_m]Hi[/name_m] there.
[name_m]Jasper[/name_m], [name_f]Pearl[/name_f] & [name_m]Felix[/name_m] are darling! They have such a cheerful vintage vibe. I think that [name_u]Sunny[/name_u] kind of fits in best, even though I personally prefer [name_f]Sylvie[/name_f]. Really [name_f]Susanna[/name_f] nn [name_u]Sunny[/name_u] or [name_f]Sylvia[/name_f] nn [name_f]Sylvie[/name_f] would be my first pick. [name_f]Luna[/name_f] is way popular & kind of trendy. I think that [name_f]Lula[/name_f] would be sweet w/your crew though.
[name_f]Hope[/name_f] this helps. 
I think [name_f]Sylvie[/name_f] sounds really nice with the other names you have! [name_u]Sunny[/name_u] does too, but [name_f]Sylvie[/name_f] matches better, in my opinion. [name_f]Luna[/name_f] does seem a little too popular, especially compared to [name_f]Pearl[/name_f] and [name_m]Felix[/name_m].
I think both [name_f]Luna[/name_f] and [name_f]Sylvie[/name_f] would be lovely with your sibset! I’m not as much in love with [name_u]Sunny[/name_u].
I think [name_f]Sylvie[/name_f] goes best with your other kiddos names! But I loveeee [name_u]Sunny[/name_u] and I think that’s my favorite name from your list. [name_f]Luna[/name_f] is too popular right now for my taste but it’s still a gorgeous name.
Oh, I just love the name [name_u]Sunny[/name_u]! The only reason it isn’t high on my list (top five) is because I have [name_f]Sunday[/name_f] as a middle name for one of my favorites. I think it’s so beautiful and just the right amount of quirky, and it works for any kind of woman in any profession. I would definitely go with [name_u]Sunny[/name_u]. It sounds perfect with your kiddos! [name_f]Sylvie[/name_f] would be my next choice.
[name_f]Sylvie[/name_f] gets my vote. It has the same vintage vibe to match your older children’s names while still sounding quite distinct – a perfect fit!
[name_u]Sunny[/name_u] is rather too cutesy and nickname-y with the others, and [name_f]Luna[/name_f] feels far more modern and popular.
All darling choices, but with your other children’s name especially I love love love [name_f]Sylvie[/name_f]! [name_m]Just[/name_m] perfect honestly.
[name_u]Sunny[/name_u] comes in next for me. There are some fair concerns others have shared, but even with those considerations it’s a solid option here, and I think literary references like [name_u]Sunny[/name_u] Baudelaire help strengthen a name that could otherwise read a little twee.
[name_f]Sylvie[/name_f] feels perfect to me!
For some reason, I just am not a huge fan of [name_f]Sylvie[/name_f] or [name_f]Sylvia[/name_f], but I do think that [name_f]Sylvie[/name_f] fits in really nicely with your sibset! [name_f]My[/name_f] preference is for [name_u]Sunny[/name_u], but I agree it’d be better as a nickname. What about [name_f]Sunniva[/name_f]?
I think [name_u]Sunny[/name_u] fits beautifully! What a sweet name!