This paper describes a novel methodological approach to reconciling points of contention (inconsistencies related to adverse and contradicting actions) when concurrently using multiple clinical practice guidelines (CPGs). The need to address these inconsistencies arises when a patient with comorbidity (the presence of one or more diseases in addition to a primary one) has to be managed according to different treatment regimens. We explain how to construct a formal guideline model using Constraint Logic Programming (CLP) and illustrate it with an example. We also present a procedure for mitigating points of contention that may arise when solving a constructed model given available patient information. The proposed procedure is conducted automatically and it employs mitigation operators that encapsulate clinical knowledge and define possible modifications to the model. The use of the mitigation procedure is demonstrated in a clinical scenario.