Like single chats, group chats are end-to-end encrypted in Threema. For privacy reasons, groups are managed in a decentralized manner on users’ devices, not on a server. Neither is it possible to transfer creator privileges, nor can creator privileges be granted to multiple users.
Cloning Groups
If a group’s creator leaves the group, a new group must be created. However, groups can be cloned. If a group member clones a group, they become creator of a new group consisting of the same members as the original group. The chat history is not transferred to the new group.
Android: Tap the title bar in the group chat, then tap the three vertical dots, and select “Clone group.”
iOS: In the group chat, tap the title bar, scroll to the bottom of the group details, and then tap “Clone Group.”
