YOU SAID:

i hope you get a cat because my sister doesn't want one

INTO JAPANESE

私の姉が欲しくないので猫を飼ってほしい

BACK INTO ENGLISH

I want you to keep a cat because I do not want my sister

INTO JAPANESE

私の妹がいらないので猫を飼ってほしい

BACK INTO ENGLISH

I do not want my sister, I want you to keep a cat

INTO JAPANESE

私の妹はいらない、猫を飼ってほしい

BACK INTO ENGLISH

I do not need my sister, I want to keep a cat

INTO JAPANESE

私は妹はいらない、猫を飼いたい

BACK INTO ENGLISH

I do not need my sister, I want to keep a cat