A lot of people are off work today, so their workload has been passed on to me.
Lots of people are sick today, so I have to cover their work as well.
この場合、pass on「回す」を受動態にして言うと自然な感じになります。
ーA lot of people are off work today, so their workload has been passed on to me.
「今日はたくさんの人が休みだから、彼らの 仕事が私に回されてきた」
または次のような言い方もできます。
ーLots of people are sick today, so I have to cover their work as well.
「今日はたくさんの人が病気なので、彼らの仕事もカバーしないといけない」
to cover one's work で「人の仕事を肩代わりする」
ご参考まで！
Plenty of people decided to take the day off today so a lot of the work got passed onto me.
ご質問ありがとうございます。
「休む人が[多い](https://eikaiwa.dmm.com/uknow/questions/34592/)ので彼らの仕事が回ってきます」は英語で「Plenty of people decided to take the day off today so a lot of the work got passed onto me.」という風に言えます。
ご参考になれば幸いです
カナダ 
アメリカ合衆国 
