Google Merchant Center Next will support rules and supplemental feeds early next year. The predecessor version, Google Merchant Center, is still used by some advertisers and already supports these new features. Advertisers that haven’t transitioned to GMC Next and want access to the rules and supplemental feeds should not upgrade to GMC Next. Those who have already migrated to GMC Next and need access to these tools can revert to classic mode. Switching back to Classic Mode may result in the loss of previously added business details and in-store product details. No return to GMC Next is possible if you switch back to the classic Merchant Center.