Microsoft Advertising has introduced Supplemental Feeds in the Microsoft Merchant Center, now available globally.
This new feature allows merchants to update specific product attributes, such as titles, descriptions, custom labels, size, color, or promotion IDs, without re-uploading the full product catalog.
Supplemental feeds are ideal for making quick adjustments to existing products. However, they cannot be used to add or remove items. Data from a supplemental feed will always override the primary feed unless removed via empty fields or feed deletion.
Only one supplemental feed is allowed per language and feed label or country, and it can be uploaded manually, via FTP/SFTP, or by URL.
Read the official announcement here: Supplemental feeds and other product news for September.