D-DAY!

The best way I have found is wait till they have all gone to bed naturally.  Then move all to where they are going to be perminanly into their bedroom.  Leave over night and let out in the morning.  There will be a bit of scuffling as they re-arrange their pecking order and this may last for a few days.  If you get one that is going for it savagely then put ther to bed again and let her out after a few hours and keep an eye out for the one they tend to pick on the most.  You must let them have a bit of a go or they will never sort out their order if you keep intervening.  They must also have enough room to go about thei business and get away from each other if needed.  This will not work if they arein a small run or pen.  Expect a few feathers to fly but do not let them commit murder.  Good luck.  Not all birds will mix but as long as they have enough room to get away they learn to tollerate each other.