auto gmai reply feature request

[ANDY LOL]

I'm working a script answer some mails have a specific label

after asnwer the mail (I setup a trigger in my test) I change label

It's not complicate to do and my tests are good, I need only to move into real situation, setup two or three things and I'm ready to go

Nevertheless when I answer manually gmail have a good feature to add the answer to the first mail,

you scroll down the mail and you have also the answer, I think name in engish is thread, since is also name of array you need to get

in methods I studied in the documentation to create the experiment

Unfortunatly when I write the mail automatically via google app script the behavior is different and the mail is not added to the first mail

(the mail I reply writing the answer)

So, exist a way I can tell to googe app script to add the asnwer to the fisrt mail? to create thread like in manual situation?

I didn't find a way, beside this, I theorically can get the body and rewrite it, this simulate the behavior,  but I dont' want to do it because of privacy,

there are too mails and variables, so I need to avoid datas go in wroing email, manually you can reply to a mail, delete all the text of the first mail

and this asnwer still is add to the thread, this is what I want to do via app script

Thanks for help