Magento 2: How to add new method in core interface?

I need to add new method to the core interface so I was checking all the Magento forums and came to know that this can be achieved via extension attributes as like in the post Magento 2 : Override core Interface and Model but my question is how can I add the arguments for that method in extension attributes. I need method as below

public function updateStatus($Id, $customStatus);

I am not sure whether I have drafted my question correctly but hope its understandable. Can anyone please give me a suggestion to achieve this?

Update: I have added new method in core module at vendor MagentoNegotiableQuoteApiNegotiableQuoteManagementInterface, it is working but my question, how can I do that in my custom module.

interface NegotiableQuoteManagementInterface
{
    /**
     * Update custom column.
     *
     * @param int $Id
     * @param string $customStatus
     * @return bool
     */
    public function updateStatus($Id, $customStatus);