To enable reporting rollup from replica servers in WSUS
You can roll up the computer and update status from replica servers to their upstream server.
To enable reporting rollup from replica servers
1. In the WSUS administration console on the upstream server, click Options, and then Reporting Rollup.
2.Select the Roll up status from replica downstream servers check box, and then click OK.
During the client scan, if the server detects that the client computer changed group membership (or name, IP address, or operating system version), it marks the client computer as needing a full rollup. The downstream server will roll up these changes to the upstream server during the next rollup after scan on the client computer.
For more info : WSUS 3.0 SP2 Reports