I want to translate:
"I gave my little sister a doll for her birthday".
I do not want to use 私
but imply that I did it, so the right particles are crucial.
I've come this far, but I'm not sure about the particle は
which I chose basically because it was the most likely one that was left.
誕生日{たんじょうび}は妹{いもうと}に人形{にんぎょう}をあげました.
My original choice was 誕生日に
but then I would have two に
s.
How can I say "for occasion"?