In one example, a network management system (NMS) and method models services in a network. The NMS identifies externally mapped attributes in a vendor neutral yang model of a network service, assigns an attribute type to one or more of the externally mapped attributes, wherein assigning includes determining, by a learning system, the attribute type of one or more of the externally mapped attributes based on an analysis of attribute types assigned to the externally mapped attributes of other network services, constructs a separate dependency graph for each of the externally mapped attributes and builds a separate hidden service model for each of the externally mapped attributes, wherein the externally mapped attribute for each hidden service model is a merge attribute for that hidden service model.