Mauritius owns these Islands, but it is controlled by the UK. Mauritius and Chacos became British colonies. Mauritius became independent later but UK did not leave Chacos. This is because of what I explained above, using it as an important military base that connect three different continents.
By now we ought to have been familiar with the way the government rules and how power tussles, the strong hands lead and that is one of the reason why the Venezuelan President was taken hostage, US could interfere on any country and make a stand, a good example is also in Nigeria, when they stated the security challenge there being a major concern.
Now about the Irelands, what can Mauritius and Chacos do when US or UK are taking charge, this is not about your right anymore, but who stand the upper chances over you against what belongs to you, i don't think we have to negotiate on this far, except that US determine to leave for good, if not, this is even the more better chance for them to occupy Chacos against Iran.