Currently, it's only possible to see the first email thread for a ticket in the customer portal. So when the contact emails a new email on the same ticket, the conversation disappears in the customer portal. This makes it confusing for the contact.
My wish here is that it would be possible for the contact to see all associated conversations from the ticket in the customer portal.
I'm David from the hapily support team! If I'm understanding your use case correctly, you need to be able to view all past comments / emails on tickets in your customer portal? We have an app that would solve your problem! Our Customer Service Portal allows you to view the entire history of a ticket's conversation along with a wide variety of customization features. Check it out in the HubSpot Marketplace.
Let me know if you have any questions. I'd be happy to hop on a call with you!