We agree this would be useful but it was not our aim to look at interactions. We also believe interactions such as suggested are better done in longitudinal studies where one can examine moderators.
Although the rationale for selecting each of the 9 factors that might be differentially related to reactive or proactive relational aggression is convincing, the overall picture is incomplete on at least two accounts. First, some factors (i.e., CU traits) may be predictors whereas others (i.e., delinquency) may be correlates or consequences of relational aggression. If the authors are really interested in the processes that could feed into reactive or proactive relational aggression in females, they should have been more attentive to this issue. Second, the authors do not mention why they implicitly selected an additive model (i.e., each factor makes a unique and independent contribution) instead of, for example, an interactional model (i.e., peer and parent factors potentiate the link between individual factors and subtypes of relational aggression).