Based on your question we could think of two alternative approaches to realize the intended behaviour:
Proposal 2. Realisation using an extend class hierarchy and relation class implementationThis approach can be realized if you update the concept how to realize "Rule Family" and "Decision Rule Family". Using the class hierarchy/inheritance concept in ADOxx, you can derive the "Rule family" class from the "Decision rule family" class and define a relation class FROM "Decision rule family" TO "Rule family". The effect of this setup is:
The relation class can be used to
a) connect a decision rule family instance with a rule family instance
b) connect a rule family instance with an other rule family instance (this is allowed since the inheritance also works on the relation class endpoint definition)
Please find the resources for implementation (example ABL, class hierarchy screenshots attached as a ZIP archive). Please have a look in detail on how the classes are derived from each other (switch to meta-model and class hierarchy)
Proposal 2. Realisation using event handling mechansismThis approach is closer to the one you had described in your message, since the type of the rule family is made available through an attribute definition ("Type"). In order to prevent wrong relation instances we can use the ADOxx event handler concept, allowing to perform certain actions when an event is triggered by the platform. The event we want to use is "AfterCreateModelingConnector". The event handler triggers and AdoScript and 2 options (warning, delete and correct) have been implemented - please remove code and adapt accordingly as you need.
Please find the resources for implementation (example ABL, class hierarchy screenshots attached as a ZIP archive). The event is added in the dynamic library's library attribute "External coupling" and executes and AdoScript made available in the file management of the library.
Since proposal 1 utilizes the actual class hierarchy mechanism of ADOxx, we recommend to restructure your conceptualization accordingly.