Simone翻译英语：如果A，B，C不在，D作为他们的代表人
的有关信息介绍如下：
有点欠缺，建议你倒过来：
D can behalf them provisionally if A，B，C are out of office.
whoever就不必用了，因为这个词表示的是“任何人”。provisionally用于修饰behalf，所以改成副词词性更好。
If A,B,C is not available, D is on behalf of them.
你想表达的是什么？
A,B,C,其中一个人不在的时候，D就可以代表他们？
还是，A,B,C 同时不在的时候，D 才可以代表他们？
我翻的是第二种情况。最好你把中文意思表达清楚点，那样对翻译更全面更完整。
D can act on behalf of A, B and C provisionally when they are not in office.
可以考虑不用provisionally
D is the authorized person to act on behalf of A, B and C when they are not in office.
aauthorized 获授权
designated person获指派之人
on behalf of代表
D shall serve as the representative of A, B and C if the latter three persons are absent.
When the agent of A or B or C is unavailable, the agent of D can be their representative.
The A、B、C ,whoever is out of office, D can be on behalf of them.
