Just a question of translation

[Neytiri101]

How would you translate "Happy Birthday Granddaughter" ?

[kewnya txamew'itan]

As an approximation (no word for birthday yet):

fpom ngaru (livu) trr ftozäyä

[Neytiri101]

is there no word for granddaughter either?

[kewnya txamew'itan]

Gah! I forgot that part. 

We don't have a word for it but 'ite 'iteyä/'itanä as appropriate should do it. 'ite 'iteyä would be for your daughter's daughter and 'ite 'itanä would be for your son's daughter.

So you'd get as the total phrase:

fpom ngaru (livu) trr ftozäyä ma 'ite 'iteyä/'itanä.

[Neytiri101]

wow great thanks, me and a friend have an inside joke where she calls me her grandma lol since i'm oldert than her, and her bday is coming up. Thanks a bunch.  Gosh I need to start learning some Na'vi fast 

[NeotrekkerZ]

There's also the stock phrase for celebrations:  Ftxozäri aylrrtok ngaru (ma granddaughter)!

[kewnya txamew'itan]

I knew there was a stock phrase! Irayo ma Neo.

The literal translation is "may you have smiles on your celebration" it's probably a bit nicer than the fpom ngaru trr ftozäyä I suggested.