Reddit reviews Process Tracing: From Metaphor To Analytic Tool (Strategies for Social Inquiry)

The research question is a little oddly phrased ("does x cause y" is vs "is x causually related to y"). The second option sounds like you're just hedging against endogeneity problems.

I think your case studies are more problematic than your question. Based off your response to u/Tony_the_Tamil_Tiger, greater production of refugees is your dependent variable. All the case studies you listed are conflicts that produced huge numbers of refugees, which implies that you chose cases on your dependent variable, which is something you must not do.

What you should do is find a number of wars in which states used proxies (and several in which proxies were not used) regardless of refugee counts. If all your cases involve large numbers of refugees, then you've got no variation on the dependent variable to explain. A good book that goes into these problems in case study construction is Bennett and Checkel (ed)'s Process Tracing: From Metaphor to Analytic Tool (Strategies for Social Inquiry