This can only be done by completely liberating the entire region of Insula Dracon. You will be able to see the locations that have not been liberated by them being red on the map. Go Rico and tear stuff up. Lots of fun with some very difficult locations for sure. If you are having a hard time liberating and areas you may have to do some challenges to level up your gear and rebel drops. I used helicopters with rockets to make some of the locations easier to clear and some were still quite hard.