In all government-supported disability plans—I'm reading from the Treasury Board cover page on public service benefit plans—Treasury Board is the benefit plan sponsor. In all of these plans, they pay the lion's share of premiums to the different insurers who cover employees of different departments.
In addition to that, each group benefit plan has a principal administrator. In this case, SISIP was created to administer this plan on behalf of the CAF members and an insurer; in this case, Manulife is the LTD insurance provider.