This paper presents our ongoing work developing service robots that provide assisted-care, such as serving tea to the elderly in care facilities. In multi-party settings, a robot is required to be able to deal with requests from multiple individuals simultaneously. In particular, when the service robot is concentrating on taking care of a specific person, other people who want to initiate interaction may feel frustrated with the robot. To a considerable extent this may be caused by the robot's behavior, which does not indicate any response to subsequent requests while preoccupied with the first. Therefore, we developed a robot that can display acknowledgement, in a socially acceptable manner, to each person who wants to initiate interaction. In this paper we focus on the task of tea-serving, and introduce a robot able to bring tea to multiple users while accepting multiple requests. The robot can detect a person's request (raising their hand) and move around people using its localization system. When the robot detects a person's request while serving tea to another person, it displays its acknowledgement by indicating “Please wait” through a nonverbal action. Because it can indicate its acknowledgement of their requests socially, people will likely feel more satisfied with the robot even when it cannot immediately address their needs.