So far not so good.... Godzilla ended up with both black and white feathers flying and can terrorize the new pullets easily. Pecking order is to be established, and it isn't a fair fight.
We've separated them in to a new protected temporary cage, but they are still stalked by Godzilla. Not idea, but we'll see how they go. In 4 weeks time they should be equal size but hopefully we don't need to wait quite that long.
Edit: So it looks like Godzilla spends much of the day menacing the other two despite the cage separating them. They also know their place and hide despite the protection.
Chickenflash: 1st October - Godzilla still menacing them through the cage although they are getting a little more brave and exploring sooner.
Chickenflash: 12 October - Gradual improvements in braveness from the pullets but looks like another fortnight before we'll mix them again. They are around 14 weeks old now.