Personally, if it were me I'd probably try to go for a name that I liked equally but that was a little more different. Having said that- if you just cannot seem to get that particular name out of your mind, and like it more than any alternatives, than just go for it. So, both names end in 'iana'- but many other names have the same ending. Would your SIL even notice if she called her daughter Hailey and you called your daughter Ashley? I doubt it.

Perhaps you can play around with Eliana- how about Elyana? Or:
Eliane
Eliah/Elyah/Eleah
Elayna
Elaiya* (my fave)
Elaise
Elaisa/Elaysa
Elise
Elisa/Elissa
Eliara