Route a contact through a flow’s logic using a ‘Split by Group Membership’ node. This will allow you to send customized messages to a contact depending on their groups.
For example, you could stop contacts who’ve already completed a previous registration flow where they’ve already been added to a group from restarting all over again:
![](https://storage.crisp.chat/users/helpdesk/website/6ce11052ec38ec00/532efc48-718a-4d06-b962-441cc1_1bjjlvt.png)
By splitting on the group membership only contacts who aren’t already added to the ‘Completed Registration’ group will continue in the flow. Those who are added to the group will receive a different message letting them know they’ve completed the separate registration flow.
You can add or remove contacts in a group either manually or via a flow.