YOU SAID:

They're there, but that's not theirs.

INTO JAPANESE

彼らがそこにいるが、それは彼等の物ではないです。

BACK INTO ENGLISH

They are there, but it is theirs is not.

INTO JAPANESE

彼らがありますが、それは彼等の物ではないです。

BACK INTO ENGLISH

They have, but it's theirs is not.

INTO JAPANESE

彼らが、それは彼らではないです。

BACK INTO ENGLISH

They are but they is not.

INTO JAPANESE

彼らが、彼らはありません。

BACK INTO ENGLISH

They are not they.

INTO JAPANESE

彼らは彼らではありません。

BACK INTO ENGLISH

They are not they.