Include multiple OCMOD XML files in one ZIP file

Question

If my extension has two OCMod XML files, is there any way to make the opencart extension installer install both of them using a single OCMod ZIP file?

The main OCMod is copied as install.xml in the OCMod ZIP file. I don't want to merge both of them into one single xml because of reusability of second file. If I keep the second file inside upload\system folder, opencart does not allow writing to system folder.

Below possibilities are already considered and client did not approve them

1. Install them as two separate ZIP files
2. Make system folder writeable

Answer 1

Is there any way to make the opencart extension installer install both of them using a single OCMod ZIP file?

No. The two options you provided are fine. If your client doesn't approve them then they are out of luck.