Updating/changing Brand name – impossible?

So I recently got an Amazon approved brand registry name. I wanted to update my current ASINs to this brand name, but the customer support rep said the only way is to create a whole new ASIN for the product and that in all cases of updating/changing brands even updating an unbranded product to a branded product required creating a whole new ASIN. A Google search showed me other people having success getting Amazon to update/change an ASINs brand after talking to basically a different rep than the one who told them no.

Is this possible? Or do I just need to go ahead and create a new ASIN?