Merge multiple zip files without unzipping (extracting)

I had a case where I had to merge multiple zip files into one, but as the size of the data was too huge (90% compressed text files) extracting and zipping them would have required 500 GB of space. So I looked for a tool that could help and I found zipmerge.

zipmerge can merge zip archives into a target zip archive. By default, files in the source zip archives overwrite existing files of the same name in the target zip archive.

-D Ignore directory components in file name comparisons.
-h Display a short help message and exit.
-I Ignore case in file name comparisons
-i Ask before overwriting files. See also -s.
-S Do not overwrite files that have the same size and CRC32 in both the source and target archives.
-s When -i is given, do not before overwriting files that have the same size and CRC32.
-V Display version information and exit.

Syntax: zipmerge [-DhIiSsV] target-zip source-zip Op source-zip ...

Source: https://linux.die.net/man/1/zipmerge