Not sure if / how this works for LDAP auth, but I know you can run your
LDAP searches against the Gobal Catalog and search multiple domains.
https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc730749(v=ws.11)?redirectedfrom=MSDN
I have been looking for through the manual and online and only found one really
solid mention of more than a single domain authentication support with
Guacamole. Basic of the setup we have a large single forest AD with several
child domains outside the primary domain that Guacamole is
