Thank you for the reply,
so if i understood correctly, I would make zentyal join my existing domain on windows server, which will replicate all the users the no issue meaning that the next day the users will not affected by trust domain, the only thing that does not replicate is the GPO but thats no issue as my gpo is real small (network drives) and i can redo it manual.
Then after that i need to transfer the roles to zentyal to make primary
and would execute the script which comes already inside zentyal
/usr/share/zentyal-samba$ sudo ./ad-migrate
then transfer the files from windows server to Zentyal
and demote normally the window server
I would guess these are the steps?
And the ad-migrate script works to transfer the roles from windows server 2012r2?
Thank you again