@GibsonAxe Once a nether portal is created the link between the worlds is created so if someone was to make a portal within the range of yours in the nether it will link to the 1 u made, even if its inactive therefore the high risk.

This is the second thread that I read stating that nether portals are permanently linked to a portal, active or not. Can you explain this? Is it to portals or the locations of portals (if you moved/removed it)?

The wiki says after 60 seconds the cached destination disappears if it goes inactive, but I don't know what that means in context to what you're saying.