Academic Writing - to decide a dissertation title and research questions

The specific topic of the dissertation is Enablers of strategic supplier relationship. The description of the topic is as follows: It is important that buying firms manage their key suppliers in a strategic manner. While there are a multitude of firm-level as well as relationship-level drivers that enable strategic as well as collaborative buyer supplier relationships, it is also important to focus on fundamental mechanisms such as trust, interdependence, opportunism as well as power asymmetry in the relationship and their effect on subsequent collaboration and win-win advantage. More importantly, these drivers not only have a direct effect on collaborative relationships. Therefore, it will also be interesting to see the mediating, moderating, as well as conditional role of the various drivers on subsequent collaboration and relationship [login to view URL] broader research topic can be approached from multiple perspectives and projects can focus on a subset of enables and their nuanced impact on strategic as well as collaborative relationships. Students need to adopt the case study approach to address their specific research question. I need you to narrow down the broad topic to select a title which can provide a relatively novel insight with a reasonable knowledge gap, and several concrete research questions. The research method is already provided which is case study approach and I need the general research proposal about how to apply the case study approach in this research topic.