Later inthe game, after reuniting a family in Macalania Woods, I was told..

To get the cloudy mirror you have to win the chocobo race in remiem temple, which you can get to by obtaining a chocobo in the calm lands, then run all the way back to the entrance of the calm lands from when you came from bevelle.

Keep heading past the entrance dont leave the calm lands, now you are on the far right of the map.

You will see a chocobo feather on the floor, press x and you will jump over a gap to another platform the go the the exit on that platform.

Now when you get turn left after the bridge dont go in the temple,there read the scroll on the floor to learn about the race. now go to the other side of the temple to start the race.

For now just concentrate on winning the race to the bottom, ignore the chests and coloured poles.

When you win you will recieve the cloudy mirrior, take this to the orb thing in the macalenia forest and it will change into the celestial mirror.

Now you can go and get everyones celestial weapons. And also you must first upgrade them with a crest and sigil before they are any good. (each charater has there own crest and sigil to find)

That should work, have fun.

If you haven't already united the boy with his mother and father then you need to do that and heres how, first your going to want to have the clouded mirror (from the chocobo race at Remina Temple or however its spelled) if you already have it go to the save point at the first screen of Macalania Woods. Right next to the save point the path should fork off and right next to the forked path there should be a woman and if you talk to her she should say that she cant find her husband or child.

After talking to her go to the right (the path that heads to Bevelle and the Calm Lands) and you want to go to the area opposite of where Tidus and Yuna get intimate in the water. Once there you should see a man in the corner. Go and talk to him and he'll say "Oh my wife is looking for me" or something and run off.

Go back to the place where the woman was and there should be the husband and her son there. Then go up to where the kid was and that area will be unblocked. Walk up to the orb and click the X button and Tidus should hold up the clouded mirror and Vwa-la the Celestial mirror. Hope I helped.

Ok heres what you do. Go down to the Mom and the Dad. Talk to them two times each. Then go back up and talk to the boy. Thats all

No one else understood the question... If you talk to the family and reunite them before having the Cloudy Mirror, you will be unable to change it into the Celestial Mirror. Very stupid but yeah, gotta ignore the family until you get that Cloudy Mirror first..