Samba4: Possible to build a AD Forest

currently I have to set up a completly new AD infrastructure. Right now most parts in that company are run by NT-DCs untill now.

I bought a new Server installing a Samba 4 (Version 4.3) domain controller on it and started to migrate all user accounts and PCs. Everything works fine. Now the branch offices should be integrated into this structure as childs with their own DCs.

TL;DR: Is it possible with Samba 4.3 to build a AD-Forest with children? If so: Is a tutorial / guide for this out there?

Thank you very much!

AFAIK this is not supported yet. There is no support of multi domain structure at both core and Samba database levels. Actually, global catalog server feature has not been implemented in Samba (once the connection request is made, it will be then redirected to the LDAP directory instead).