The responsibility for staffing and approvals of the RSSP should be based on whom is responsible for the sustainment of the system.  They would know how they are going to continue to sustain it while the replacement system is developed and fielded.   Therefore it would be a Service determined process with Service approvals.  As for being included in the LCSP of a ACAT ID program, the LCSP would go through the OSD review with the annexes provided by the various contributing stakeholders.  As I'm sure you know, the PSM relies on the cooperation of many stakeholders outside of the Program office for support in meeting the overall Product Support Strategy and for information included in the LCSP.