I actually like using [name]Elliot[/name] for a girl…maybe to get a more feminine feel, you could spell it Elliet (like [name]Juliet[/name]) or Eliett (like [name]Scarlett[/name]). I always thought [name]Eliot[/name] was a kind of girly boy’s name. Maybe you could push the name a bit further and go with Elietta like [name]Julietta[/name]. This totally eliminates the masculinity/femininity problem of [name]Elliot[/name]/[name]Lilia[/name] but then potentially creates a problem with “making up” names.
A couple more suggestions to get the nn [name]Elle[/name] but with a more feminine full name ([name]Lilia[/name] is terribly feminine, in a wonderful way), [name]Elspeth[/name], [name]Elizabeth[/name], [name]Helen[/name], [name]Elena[/name], (I was going to suggest [name]Elise[/name] as it is a name on my list, but it seems that is your name… how do you like being named [name]Elise[/name] by the way?) [name]Elia[/name], [name]Ellen[/name], [name]Nelle[/name], [name]Penelope[/name], and many more… I would say each of these out loud with [name]Lilia[/name] and see how it feels to you.
You could also go for the nn [name]Etta[/name] or Etie which would probably save your kid many years of [name]Ellie[/name] X in classrooms full of Ellies. You could go with [name]Scarlette[/name], [name]Violet[/name], Eliotte, [name]Charlotte[/name], etc.,
Here’s my thoughts on your lists…in general I love your choices
Girls:
Elliotte [name]Wren[/name] (also like [name]Pearl[/name] as a mn) nn [name]Elle[/name]—I like Elliotte [name]Wren[/name] better than [name]Pearl[/name], see notes above
[name]Averie[/name] [name]Pilar[/name]–I am not a huge fan of [name]Averie[/name], but love [name]Pilar[/name], what about [name]Pilar[/name] [name]Averie[/name]
[name]Isla[/name] [name]Marie[/name]–I would suggest also using [name]Pilar[/name] as a mn here, [name]Isla[/name] [name]Pilar[/name]
[name]Scarlett[/name] [name]Averie[/name]–I think [name]Scarlet[/name] [name]Marie[/name] sounds a bit better and would be easier to say. [name]Averie[/name] seems to break the name up a bit.
Boys: such classic choices! I don’t dislike any of your choices here…I also don’t find them quite as exciting as sister [name]Lilia[/name]. Something also to keep in mind is that [name]Lilia[/name] and [name]William[/name] definitely rhyme, and if you’ll be having a third (on accident or on purpose) finding a third name that doesn’t sound totally out of place may be difficult for you. [name]Even[/name] [name]Lilia[/name] and [name]Willem[/name] are very similar sounding names. Then again,…you always have [name]Elliot[/name]… My favorite is [name]Carter[/name] [name]James[/name] (even though every [name]James[/name], [name]Jimmy[/name], [name]Jamie[/name] I’ve met has been a jerk). Some names that go with your style but excite me more are [name]Jack[/name], [name]Oliver[/name] (nn [name]Ollie[/name]?), [name]Charles[/name] (nn [name]Charlie[/name]), [name]Harry[/name], [name]Sebastian[/name], and [name]Lucian[/name]. Also, you could go with one origin of [name]Lilia[/name] and match the other name to it…For instance, Latin boys names [name]Adrian[/name], [name]Amias[/name], [name]August[/name], [name]Bastien[/name], [name]Caio[/name], [name]Cassian[/name], etc., (if you do a name search for boys with a Latin origin, there is a really great list of names that would go well with creative, whimsical, beautifully strong [name]Lilia[/name]).
Best of luck to you! Let us know how the decision turns out.