Haddock, introduced in [11], is a declarative language and architecture for the specification and the implementation of Multi-valued decision diagrams. It relies on a labeled transition system to specify and compose individual constraints into a propagator with filtering capabilities that automatically deliver the expected level of filtering. Yet, the operational potency of the filtering algorithms strongly correlate with heuristics for carrying out refinements of the diagrams. This paper considers how to empower Haddock users with the ability to unintrusively specify various such heuristics and derive the computational benefits of exerting fine-grained control over the refinement process.