Introducing my rats, help?

[muncher]

I picked up two 6 week old girls on the 16th of jan 2011. I originally had two castrated males and one female in the same cage together. For the first couple of weeks I kept the babies quarantined in case they were carrying anything. I then placed them cage by cage for around 3 weeks and taking them out on the bed together every day for an hour or so. There was the odd fight which is to be expected, other than that they were fine together. So today I cleaned the big cage out and moved them in together. The little ones seem to be generally nervous of the big ones in the new cage at first (but were not out of the cage) The small brawls broke out as again to be expected. They have seem to have taken to the adult girl as 'mother' rat and follow her everywhere and she doesn't seem bothered by this now and has even been grooming them. One of the males is taking no notice of them, and doesn't seem to bothered. The 4 of them will happily sit with each other in their hammock.

Now our biggest rat, the other boy, I suppose he is Alpha (nearly 2, albino. And I know again to expect the dominance fights) isn't going to look for them, but if they come near him he'll either:

1. puff up, maybe hiss, and sometimes if the little ones try to run, he'll pull at their fur, sometimes quite hard. He hasn't broken skin or drawn blood though.

2.or when they come face to face they'll come close to touching noses and go very very still, and he might put his head under them, without puffing up or hissing.

Also if he is eating and the babies go over to him, he doesn't lash out he just turns away as if he would with the other rats.

Its only him now who has a 'problem' but he's not looking for them, and its not like instant fighting if they come over.

They just seem to be nervous of him, but not the other two.

Is this something I just need to watch and let it play out and be ready with a squirt bottle. Or should I split them up again?
maybe an age thing? We've introduced babies to him before and he's been fine, and he's taken to them in a week of first meeting to living together.