Yes. You can manually update the content that the GUP gives out.
But, keep in mind that the content the GUP hands out is different from the content that the GUP client is using. For example the SEP client that is a GUP is using content revision 9 (which could be the latest) but the GUP cache only has content revision 8 then the GUP can only hand out content revision 8 until it downloads revision 9 from SEPM. It does not matter what the SEP client is using it maters what the GUP has cached.
The GUP cache is stored in the SharedUpdates Folder:
SEP 11 - C:\Program Files\Symantec\Symantec Endpoint Protection\SharedUpdates
SEP 12.1 -
- (32 bit machines) C:\Program Files\Symantec\Symantec Endpoint Protection\12.1.x.x.x\Bin\SharedUpdates
- (64 bit machines) C:\Program Files(x86)\Symantec\Symantec Endpoint Protection\12.1.x.x.x\Bin64\SharedUpdates
You can manually copy files to this folder for the GUP to use as long as the file names and paths of the files you manually add are correct.
Keep in mind that the GUP will only give out files that the remote client requests. So for example if a client asks for a delta file from rev8 to rev9 and the GUP has the full rev9 content file but does not have the delta file then the GUP will download the delta file from SEPM, even though it has the full content file for rev9.