The phrase "act as their representative" is correct and usable in written English.
It can be used when referring to someone who is authorized to speak or make decisions on behalf of another person or group.
Example: "In the meeting, she was asked to act as their representative and voice their concerns."
Alternatives: "serve as their delegate" or "represent them".
The four priests asked a senior figure in the diocese to act as their representative to the nuncio's office.
But they would be assigned a United States military official who would act as their representative, helping gather witnesses and evidence, including classified material, to challenge their detention before a military-appointed review board.
But it meant that not even the Klebnikov family was permitted in the court room they hired Larisa Maslennikova, an attorney who helped craft Russia's criminal code, to act as their representative.
In the case where the number of leading nodes is greater than eight (i.e., the number of all ad hoc nodes is greater than 64), they also need to elect leading nodes in their group that will act as their representatives to the ad hoc network.
The protestors have apparently been offloading some of the associated organization and negotiation logistics onto the Independent Workers Union (IWGB) Couriers & Logistics Branch, which claims to have acted as their representatives in talks with Deliveroo.
The proposal which bore the signature of Francisco Lastres and Eulogio Despujols, who acted as their representatives, was ultimately accepted.
Participants also described that committees involving their leaders were usually active when disasters happened, and that those leaders acted as their representatives on issues of participation when dealing with the Government and relief agencies.
Other countries, such as the UK, have allowed the clinician responsible for the care of the patient to act as their legal representative, as long as they are not connected to the conduct of the trial and that there is no person with a closer relationship to the individual willing or available to act.
Agents act as their clients' representative in dealings with team owners, coaches, and executives.
Group members act as representatives of their group in order to improve the situation of their entire group.
In the United States, for example, the Securities and Exchange Commission delegates substantial authority to self-regulating organizations (SROs), which act as representatives of their industry who can design and implement rules that govern the practices of their members (Stefanadis, 2003).
