Container Rules Manager od Sarcastic Bird

Container Rules Manager gives you a full table view of your Multi-Account Containers site assignments. Add multiple sites at once with comma-separated input, reassign sites between containers, bulk delete, and import/export rules as JSON for backup or migration.

Requires a native messaging host (Go binary) to read and write MAC's database. See the GitHub repository for installation instructions.

How it works: Multi-Account Containers locks its database while enabled. Temporarily disable MAC via about:addons, make your changes, then re-enable it. The extension detects MAC's status and guides you through this process.

https://github.com/sarcasticbird/fmac-rules-manager