Feature interaction is a common problem in feature generation methods such as incremental feature generation, automatic feature extraction, feature-based design and manual feature definition. Research on feature interaction involves analysing the interaction relationship, decomposing the interacted features into atomic or single features, and defining their relationship, human interpretation being required. The paper presents an approach to handling the feature interaction problem in incremental feature generation. As a protrusion or depression feature is defined, the interaction between the features is analysed. The relationship is then defined and the interacting existing feature is redefined according to the interaction cases. The approach involves feature existence analysis and modification procedures. The existence analysis classifies the existing features into three groups; features remaining without interaction, features to be removed, and features remaining after being partially removed. It further classifies the last group into only the face set being removed, only the boundary edge path being removed, and the face set including the boundary edge path being removed. The three interaction cases in the last group require modification procedures. The modification procedures are (a) decide whether the remaining part of an existing feature is valid for a feature definition, (b) update it as a new feature, and (c) define the feature's relationship. The above procedures are performed through tracing the Boolean operations and convexity of an intersection edge loop generated during design evolution.