To merge Amazon listings, you need to follow these steps:

1. Create a new product description: Create a new product description on Amazon, which includes the brand name, product description, price, and other important information.

2. Modify the existing product description: Add the brand name of the existing product description to the newly created product description so that all customers can access these products.

3. Merge products to Amazon warehouses: Merge products from two or more brands into Amazon warehouses. This can be done by adding the products to Amazon's "Products in Warehouse" page.

4. Update product information: Before merging, make sure that the product information, including price, description, and pictures, has been updated to ensure that all customers can understand the product correctly.

5. Submit a merge request: Submit the merge request to Amazon and make sure that all necessary information is accurate and complete.

Please note that merging products from different brands may increase the load on Amazon's servers, so the merging process may take some time.