@FN-GM it should do this by default:
Membership rule is set top update on a schedule (1 day) and to dynamically add new resources
I then have a query to get the computers:
What this does is:
select SMS_R_SYSTEM.ResourceID,SMS_R_SYSTEM.ResourceType,SMS_R_SYSTEM.Name,SMS_R_SYSTEM.SMSUniqueIdentifier,SMS_R_SYSTEM.ResourceDomainORWorkgroup,SMS_R_SYSTEM.Client from SMS_R_System where SMS_R_System.SystemOUName = "<dns.domain.name>/DOMAIN CONTROLLERS" or SMS_R_System.SystemOUName = "<dns.domain.name>/PATH/TO/PARENT/COMPUTERS/OU"
Show the DCs in the DOMAIN CONTROLLERS Container
and starting at <dns.domain.name>/PATH/TO/PARENT/COMPUTERS/OU and everything below that..
I then create more collections inside this collection to replicate my AD structure, but just deepening the OU Path (eg: <dns.domain.name>/PATH/TO/PARENT/COMPUTERS/OU/SUB-OU1)