Your best bet is to keep quiet and listen to the half gist from wherever you joined. If the opportunity to join in presents itself, feel free to join in.
But do that at your own discretion. Believe me, you don’t want them to wrap up the half gist and make you a full gist.
After Chatting with Tony, Isabel chats up her younger sister, Esther. They talk about what Tony and Isabel had discussed, as well as tell us