Offline WSUS delta updates

I have a secure (not connected to the internet) system that needs to be kept up to date via WSUS. We have installed a WSUS server on it and have copied over 20+GB of update content and imported the corresponding configuration for them.

Now, a month later, we want to only add the 27 new updates from Microsoft, but we can't figure out a way of exporting only the new changes from out internet connected WSUS machine so we don't have to impex the whole 20+ GB again.

Is this supported by WSUS (Server 2008 R2)?

I don't know if you can chose exactly which updates should be downloaded using WSUS Offline Update. But at least you can download the patches and delete everything unwanted.