Adding multiple custom target systems

We have a requirement to have multiple custom target systems. Syncing data from the first one works fine and data is added from target system to UNSAccountB, UNSGroupB and UNSAccountHasUNSGroupB tables.

However when we start syncing the next one, the sync process wants to delete all existing accounts, groups and memberships from UNSAccountB, UNSGroupB and UNSAccountHasUNSGroupB tables and insert those from the other target system. We do have the process set up in workflows so that objects that only exist in One Identity database should be deleted, but what we would need here is that it would only consider those systems which match this custom target system (match the UNSRootB key in UNSAccountB and UNSGroupB tables).

Have we missed something setting up our sync or is there no way to limit the delete scope for this operation?