YOU SAID:

how does one do of the do if they are not doing?

INTO JAPANESE

彼らがやっていない場合、どうすればよいのでしょうか？

BACK INTO ENGLISH

What if they do not do, what should I do?

INTO JAPANESE

もし彼らがしなければ、私は何をすべきですか？

BACK INTO ENGLISH

If they do not, what should I do?

INTO JAPANESE

もしそうでなければ、私は何をすべきですか？

BACK INTO ENGLISH

If not, what should I do?

INTO JAPANESE

そうでない場合、私は何をすべきですか？

BACK INTO ENGLISH

If not, what should I do?