Elsa and Esther

Do [name_f]Elsa[/name_f] and [name_f]Esther[/name_f] sound too similar for sisters?

Yes, a bit too matchy.

Take it from someone who married into a family with a [name_m]Joshua[/name_m] and a [name_m]Josiah[/name_m]: if they sound too similar or are spelled too similar, they will be swapped and confused at times. (Such as when the accountant mixes up their tax information! Not good, for them personally, or for the “professional” accountant!) If you have any doubts, I would avoid this possibility…

On their own, no. But consider I’d they have nick names. [name_m]Will[/name_m] they both be [name_f]Ellie[/name_f]?

No. [name_m]How[/name_m] do you get [name_f]Ellie[/name_f] from [name_f]Esther[/name_f]?

A bit too matchy, imo.