Not sure but I picked Attina because she also looks the most like her mother along with Ariel

Her face looks very similar.

Definitely. I think she looks like a slightly younger Ariel with brown hair.

But she's older than Ariel

I think that Alana and Adella are the ones that look more like Ariel.

None of them really.

All seven of them look alike the only difference is the hair, eye color, tail color, and shell color

Just the hair's different really.

I think they're all quite unique, but Adella's features, from further away, seem to have the some soft quality as Ariel's.

If she had red hair

or Adella