Easier Nether Portals Linking

I was playing on a Java server with my brother and I was trying to link up two portals. One with to the roof and one in the normal nether and both portals in the overworld lead to the roof. So I think you should be able to put a sign of the linking is not working with coordinates of the portal you want to link up to (but still near the "real spot" for the portal just if it is not working).