Unable to add more option values on existing product

Shopify Partner
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I have created some products and added one option and some values in it. Now I need to add 2 more options and some values in each of the new options. But I unable to add new value in existing option, also I unable to add more than one value in new option. It shows "You can add only 1 variant at a time. Remove commas and try again". There is no document found that how to add new values to the existing option. There is no API found to update product with new values in existing options.

How do I create new values to the existing options