YOU SAID:

i wish my horse had a horse that had a horse that had a horse

INTO JAPANESE

私の馬には馬がいる馬がいたらいいのに

BACK INTO ENGLISH

I wish my horse had a horse.

INTO JAPANESE

私の馬にも馬がいたらよかったのに。

BACK INTO ENGLISH

I wish my horse had one too.

INTO JAPANESE

私の馬にもそれがあればいいのにと思います。

BACK INTO ENGLISH

I wish my horse had that too.

INTO JAPANESE

私の馬にもそれがあればいいのにと思います。

BACK INTO ENGLISH

I wish my horse had that too.