Add files to the existing archive in XZip, C++, Windows - c++

Question

I am creating a windows service that periodically copies the contents of a folder to an archive. I've searched for archiving libraries and found suggestions to use XZip.
Now I can create a new archive using code like this:
HZIP arch = CreateZip((void*)Archive.c_str(), 0, ZIP_FILENAME);
if (arch == nullptr)
return addLogMessage("Unable to open archive.");
for (const auto& file : std::filesystem::directory_iterator(Directory)) {
const std::wstring filePath = file.path().wstring();
const std::wstring nameInArchive = file.path().filename().wstring();
if (ZipAdd(arch, (TCHAR*)nameInArchive.c_str(), (TCHAR*)filePath.c_str(), 0, ZIP_FILENAME) != ZR_OK) {
std::string what = "Error: Adding '" + std::string(filePath.begin(), filePath.end()) + "' to the archive.";
addLogMessage(what.c_str());
}
}
CloseZip(arch);
I also want to add files to an existing archive. When I run the code below, I get a ZR_ZMODE error from the ZipAdd function, which means tried to mix create / open zip archive:
if (std::filesystem::exists(Archive)) {
HZIP arch = OpenZip((void*)Archive.c_str(), 0, ZIP_FILENAME);
if (arch == nullptr)
return addLogMessage("Unable to re-open existing archive.");
for (const auto& file : std::filesystem::directory_iterator(Directory)) {
const std::wstring filePath = file.path().wstring();
const std::wstring nameInArchive = file.path().filename().wstring();
if (ZipAdd(arch, (TCHAR*)nameInArchive.c_str(), (TCHAR*)filePath.c_str(), 0, ZIP_FILENAME) != ZR_OK) {
std::string what = "Error: Adding '" + std::string(filePath.begin(), filePath.end()) + "' to the archive.";
addLogMessage(what.c_str());
}
}
CloseZip(arch);
}
I assume that in XZip library, I'm not able to add files to the existing archive. Is it true?
EDIT: I've solved the problem with different library, libzip. Now I can add new files to the old archive, and everything works fine. I've posted source code and compiling/linking instruction here.
I am still interested, if there is an option for adding files to the existing archive in XZip library, so I will not close the question for now.