I reckon.. put a blonde wig on Esme and あなた get Rosalie and if あなた put a brown wig on Esme あなた get Rosalie so i reckon that they should of just done that because, yeah, your right, Esme does look younger than Rosalie.... anyway..... that's just my opinion....
No i think Elisabeth Reaser looks older than Niki, she looks her age thought i'd guess niki to be around 23, 24....you can tell she's older, it's around the eyes