How to add custom responses in dialog task for webhook channel enabled in Smart Assist

Hi Team, we have already built chatbot on XO platform with custom webUI and it is integrated using webhook and now we are trying to migrate it to smart assist. By enabling the webhook channel in Smart Assist, we are unable to get the existing webhook responses on the chatbot and unable to see smart Assist webhook in the dialog task response selection dropdown. can somebody help us how we can do that ?