I love [name_f]Aviana[/name_f] and [name_f]Eliana[/name_f] for sisters, but i am convinced they are just too similar! I was thinking maybe a double barrel name would make them sound different. [name_m]How[/name_m] about a mixed name (like [name_f]Annabelle[/name_f]= [name_f]Anna[/name_f] + [name_f]Belle[/name_f])
Here is what i have so far:
[name_f]Eliana[/name_f]-[name_f]Joy[/name_f]
[name_f]Eliana[/name_f]-[name_f]Renee[/name_f]
AvianaRose?
Sincerely, [name_u]Jules[/name_u] 
I think those names sound good together as fn/mn combos (I particularly like [name_f]Eliana[/name_f] [name_f]Joy[/name_f]). But I don’t think it changes the fact that [name_f]Eliana[/name_f] and [name_f]Aviana[/name_f] are very similar, and I prefer them without hyphens. But if you absolutely love them together, go for it! [name_m]Plenty[/name_m] of parents choose matching sibling names, especially for twins. I think if they had different sounding nicknames, eg. [name_f]Ellie[/name_f] and [name_f]Avia[/name_f], it would be better.
I agree with Emsky – adding another name to one or the other doesn’t take away the fact that the two are very similar. I love her suggestion of [name_f]Avia[/name_f]. I like [name_f]Eliana[/name_f] [name_f]Joy[/name_f] and [name_f]Aviana[/name_f] [name_f]Rose[/name_f].