I have developed an indicators based assessment framework for evaluating quality of governance of stakeholder participation in decision-making within development projects, and more broadly.
Have you thought about SNA (Social Network Analysis). There are several free software applications available online. They would enable you to analyse connectivity and by ascribing weighting to relationships you can identify key nodes/organisations. In my opinion SNA works best in conjunction with other methods (such as semi-structured interviews with key informants, or survey data).