Two small problems caused by splitting the database

[pete31]

Take a look at Script: Create or change smart group(s)

Especially this part (checking if a record at a location exists) could be useful:

@pete31

if not (exists record at ("/" & theMetaGroupName & "/" & theSmartGroupName) in theDatabase) then
	set theSubsetsSmartGroup to create record with {type:smart group, search predicates:"kind:smart group", search group:theDatabase, name:theSmartGroupName, exclude from search:true} in theMetaGroup
else
	set theSubsetsSmartGroup to get record at ("/" & theMetaGroupName & "/" & theSmartGroupName) in theDatabase
end if

You’ll have to study the script on your own