email in the same tread

[dpavlov]

I have a bot that generates a PDF invoice and sends it to the customer. I created another both using the same exact email template that sends a reminder email for unpaid invoices. However the second email does't go in the same tread as the first although the subject and the sender are exaclty the same. 

Any ideas how to get the reminder email in the same tread in Gmail? 

[SkrOYC]

This seems like a Gmail question more than an AppSheet one.

I think that it's not possible since each email have metadata on the header so I guess that when you reply an email it's metadata is passed to the new one to have control over which email was replied even if the subject is the same