Once we had a similar setup, only 2 factions.
And yeah, guess u fucked up sth. When trying to load your mission in Eden, it says one
} is missing. Didn't want to look for other mistakes, so I downloaded the original pbo.
Unpack your pbo, so u have the folder. Copy this folder to directory documents/arma3 other profiles/your name/mpmissions.
Then open your Editor and load this mission.
On one little island in the south you should see this:

Removing side
Delete all red (OPFOR) markers. But take care, don't delete the save zone marker! When done, it should look like this:

Removing side
Save your mission and repack to pbo, upload and have fun.