I am a bit confused on how to properly upgrade my servers to OES2sp3. I have read the documentation.

They currently run SLES10sp3 with OES2sp2.

I want to do an offline upgrade if possible.
I have upgradeded the servers in the past from SLES10sp2 with OES2sp1 to SLES10sp3 with OES2sp2 using the DVD/CD.
Because the server already has SLES10sp3 (with post sp3 patches) on it this is not possible?
Should I wait until SLES10sp4 is available to upgrade them both at the same time?

Is it possible to use "patch CD update" in Yast2?