A familiar group becomes welcoming when its history does not occupy every available topic.

Long friendships build up a shared record that is genuinely enjoyable to visit: the references, the running jokes, the story everyone knows. The difficulty is that all of it is closed to anyone who was not there. A newcomer can sit through an entire evening with nothing to contribute, not because they were unwelcome but because there was no subject available to them. Nobody intends this, which is why it happens so often.

When someone new joins the table, put at least one topic on it that has no history attached. Ask them something, and follow it far enough that the conversation lands in the present rather than looping back.