The reason behind my idea is a bit different. I am looking for more flexibility when setting rules for file groups. Since having multipe entries for one application is not possible, I thought that where and when found necessary to set exceptions within a file group, it could be added through the interface - as I have ideated.
As applications are grouped on the grounds of behavioural similarities, it is highly likely that one or many application(s) in a file group might require access(es) which is/are specific to it/them. It is also very likely that one of these accesses, if allowed for applications that do not need it, will render the system vulnerable.
That is why I had thought up this idea so that accesses could be set on a per-application basis within file groups.
Your idea would extend this. It might make it more confusing to use as the exceptions for the top rules would be targets and the exceptions for the lower rules (your ones) would be the application. Some advanced features like this could be invisible unless an advanced option was ticked.
Won't be a probelm as Defense+ would search all across the "Computer Security Policy" for a matching rule. I feel, an order-based rule preference is better applicable to the firewall.