[name]Quinn[/name] is an underused, unisex name that is adorable on a girl but powerful on a woman, that definitely matches [name]Elliott[/name] and [name]Lincoln[/name] very well! I hope it can grow on you!
[name]Quinn[/name] [name]Jayne[/name] isn’t a great combo, it’s OK, but [name]Quinn[/name] [name]Josephine[/name] I really like! If she wants a nn like [name]Elliot[/name] has [name]Ellie[/name] - [name]Quinn[/name]-[name]Jo[/name]? Quinsie/[name]Quincy[/name]? That one could come both on its own and also from [name]Josie[/name] in [name]Josephine[/name]. More nns from the middle might be [name]Fina[/name] or Finna, both from [name]Josephine[/name] and from rhyming [name]Queena[/name] Feena/[name]Quinna[/name] Finna. Also [name]Posey[/name] from [name]Josephine[/name], because with [name]Quinn[/name], it’s like minding your Ps and Qs ; ).
Now to the others: I think that since the point with [name]Elliott[/name]'s name was to go with a family name, it’s not essential than the second name be as boyish. I can understand the desire to have it be so, but it wouldn’t be crazy to go more feminine.
[name]Vivian[/name] - I don’t know how much it’s really going to skyrocket? I guess it could. But with this name and [name]Eva[/name] both meaning life, it seems really fitting to use one or the other. While it’s much more feminine in current usage than [name]Elliott[/name], it does have a history of use as a boys’ name, so I can see it working. Other life names if you are willing to go flexible, especially with two family tree names meaning life: [name]Viva[/name], Vivette, [name]Liv[/name] (the Scandinavian name, not as a nn for [name]Olivia[/name]), [name]Enid[/name], [name]Zoe[/name]. Not sure any of those work better? I think [name]Vivian[/name] [name]Jayne[/name] is the better mn combo.
[name]Eva[/name] - it is quite popular, but not over the top currently, and beautiful. I see why you like it. Again since it relates to [name]Vivian[/name] it’s sort of a double family-name. You’re OK with two E names I take it? It’s a different name, but again, if you’re flexible, [name]Evan[/name] would honor both [name]Eva[/name] and [name]Vivian[/name] and go with the non-traditional feminine use of [name]Elliott[/name]. [name]Just[/name] a thought. Again, if you’re flexible, [name]Evelyn[/name] is a little less popular, I think, also kind of merges [name]Eva[/name] and [name]Vivian[/name], and also has a history of masculine use. [name]Josephine[/name] is the better middle name here, I think.
[name]Scarlett[/name] - can you come to like this one more with [name]Elliott[/name] by seeing their shared literary heritage (T.S. [name]Elliott[/name], [name]George[/name] [name]Elliott[/name], [name]Scarlet[/name] Letter, [name]Scarlett[/name] O’hara), and [name]Scarlett[/name]'s strong sound even if she’s really feminine? They both end in T, and [name]Scarlett[/name] has [name]Carl[/name] in there so she could be [name]Carly[/name] as a nickname. [name]Ellie[/name] and [name]Carly[/name] is cute. So is [name]Ellie[/name] and [name]Lettie[/name].
Again on the flexibility thing: would you consider a daughter named [name]Jay[/name] to honor [name]Jayne[/name]? It’s also a bird name so it kind of works to me even though it’s masculine sounding, like [name]Wren[/name] or [name]Lark[/name]. [name]Jay[/name] [name]Josephine[/name] is OK, but [name]Jay[/name] [name]Vivian[/name] is really nice to me.
[name]Hope[/name] that helps! All best!