Combining fields through hierarchical structures

Hi All,

I've been having problems carrying a specific group index through a hierarchy of product groups (custom made entity). As of now i have two fields in each Product Group, one for a "group index" and one for a "family index".

This is a table to illustrate how i would like the family index to be stored.

Creating a "Family Index" simply by using a calculated field (Family Index = Parentgroup.Familyindex + Group Index) is not possible since it could create a cyclical reference.

I have tried making a third field for storage of the "Family Index" field, which is used by the calculated field in the child group to avoid the cyclical reference. The copying between the fields would then be handled by a workflow.

Now to the problem.

My solution using workflows and calculated fields is working when a new record is created and if you change the "Parent group". However, the "Family Index" is not changed for child records when the "Family Index" of a parent is changed. This is because a calculated field seems to have limitations triggering a workflow, so a change in the storage field does not trigger. A workflow does not seem be able to trigger on a field change on a parent record either.

Is there a better way to build this entity?

Through a lookup i am going to use the Family index together with a product number to create a product index with another added "product suffix". It is also important to know that the structure should be expandable and that is why i want this index to be collected recursively.

Thank you in advance,

Adam