This study proposes a method via which to support smooth rejoining in a face-to-face group chat for a participant (the leaver) after they have temporarily left, without interrupting the conversation. A previous study demonstrated that presenting a summary containing much of the recent conversational content to the leaver immediately before their return facilitates smoother rejoining for the leaver. However, because the conversation involves all participants, the issue of rejoining concerns not only the leaver but also those who continued the conversation (the conversers), who should be supported in continuing their conversation smoothly, without disruption. Therefore, in this study, we attempt to support smooth rejoining for both the leaver and the conversers. We propose a method of sharing common conventional information with both parties and discuss the effective types of information to share: a summary and keywords. An evaluation experiment suggested that sharing a summary enhances the leaver’s sense of being able to rejoin early and their ease of understanding the conversational content. Furthermore, sharing the summary reduced the conversers’ sense of the time required to explain the conversational content to the leaver. However, we could not confirm the effectiveness of sharing keywords in facilitating smooth rejoining. These findings suggest that when sharing common information before the leaver returns, it is important to share information that allows both parties to grasp the conversational content with the same level of detail and ease.