Hi Sylvie,
Sorry for the delay.
Yes, you can insert file in the zip and save it as a new zip file. Here is the code snippet:
ZipArchive zip = new ZipArchive();
zip.Open(@"C:\Backup_131128_1707_f4031493.zip");
StreamReader reader = new StreamReader(@"C:\Solinium2.config");
zip.AddItem(@"Methods\Solinium2.config", reader.BaseStream, false, FileAttributes.Archive);
zip.Save("Test.zip", true);
Please try this and let me know if you have any other questions.
Regards
Geetha