Creating list entity with multiple regex entities

I need to understand how can I create a list entity that contains other regex entities.. I am able to create multiple regex entities but unable to combine them. So, I have a regex entity that identifies an Incident ticket number, one that identifies request and one for request item. Now when I want to ask the user if they have an existing ticket or not and if they have already mentioned a ticket number in the conversation, I am unable to verify it due to the lack of list.