Create and manage all your merge rules from the dashboard. You can create a maximum of 4 Profile Merge Rules.
The fourth Profile Merge Rule (All Cross-Device Profiles) is only available to customers who purchase the People-Based Destinations add-on.
The Profile Merge Rules dashboard provides a unified workspace that lets you manage your Profile Merge Rules. The dashboard is located at Audience Data > Profile Merge Rules. Your rules dashboard could look similar to the example shown below.