      addBtn.innerHTML = '<i class="bi bi-hourglass-split"></i> Adding...';
        addBtn.disabled = true;
        
        try {
            // Add devices one by one
            const promises = window.selectedDevicesForCase.map(deviceID => 
                fetch('/api/v1/cases/' + window.currentCaseID + '/devices', {
                    method: 'POST',
                    headers: { 'Content-Type': 'application/json' },
                    body: JSON.stringify({ device_id: deviceID })
                })