The steps to merge variants on the Amazon platform without using templates are as follows:

1. **Create self-delivery links**: You need to create self-delivery links for each of the two children (variants) you want to merge. This means that you need to set the delivery method of these two children to self-delivery in the Amazon backend.

2. **Create parent**: Create a parent product, which should also be self-delivered. In the Amazon backend, you can add new products and set the appropriate product status for them.

3. **Add children to parent**: After creating the parent product, add the self-delivery children created previously to this parent. In this way, the two children are associated with the parent to form a variation combination.

4. **Confirm variation relationship**: After completing the above steps, check whether the variation relationship has been correctly established. In the "Manage Inventory" or "Catalog" section of the Amazon backend, you should be able to see that the variation relationship between the parent and the child has been successfully created.

5. **Monitor variant status**: After merging variants, continue to monitor product sales and customer feedback to ensure that the variant relationship is stable and has not been automatically split by the Amazon platform.