[Samba] create new child windows domain in existing samba forest

[Cobra Koral]

Hello guys. Continuing Zhuchenko Valery question,I would like to know if someone from the list has deployed a child domain in samba 4.
I have a samba 4 domain controller running on gentoo.My goal is to set up a domain and authentication domain only. But I need a root domain forest and a child domain.I am using verion 4.2.11I would like to know if someone has accomplished this either using dcpromo or though samba native commands.
net-fs/samba-4.2.11::gentoo was built with the following:USE="acl addc addns cups gnutls pam quota winbind -ads -aio -avahi -client -cluster -dmapi -fam -iprint -ldap (-selinux) -syslog -system-mitkrb5 -systemd -test" PYTHON_TARGETS="python2_7
Since Valery reported error using dcpromo, I would like to get some feedback from the community before trying.
Thanks in advance