GMail reply to specific email

How are you guys replying to a specific email, that the email chain would be easily visible then later user opens to his GMail?

Don’t wanna do it via UI, but also don’t wanna create new email by building it like Subject = "RE: " + previous Subject as it would be count as a total different email and wont be visible in email chain.
Sorry but couldn’t find proper activity to do so ;(

Hey @latke

Please try this with Use Gmail → Reply To Email