Guide on how to repair (and properly install) OCLP when I have Windows (Bootcamp) installed and present in the EFI boot menu

I already found this github post with some pointers: https://github.com/Dortania/OpenCore-Legacy-Patcher/issues/972#issuecomment-1046126535

Current situation: I had my internal disk with a GUID partition map, with 3 partitions: APFS for MacOS, NTFS for WIndows, and an Unknown 3rd partition of 471.9 MB (I guess this is the EFI partitions). Until I installed OCLP, i had MacOS and Windows in the boot menu when holding down the Options key at boot. After I installed OCLP and asked it to install itself on the internal disk, I now only have "Windows" as a label, which is actually the MacOS via OCLP (see above link) and no separate actual Windows, so I can't boot into Windows any more.

Can a kind soul please outline some ELI5 steps to fix all this such that:

- I can boot without any USB drive (install OCLP on the internal disk)
- I get both MacOS and Windows in the boot menu via the Option key (and so I can actually boot into either MacOS or Windows)
- Make the MacOS entry the default so I don't need to press the Option key.

I understand I need to uninstall OCLP and create a separate EFI partition for it ... but given I have no free partition space on the disk, it would mean somehow shrinking the existing EFI partition (preferably? rather than shrinking the Windows one before it) in order to make room for an extra partition, then create a new partition and install there.