It depends on how severe the bullying is - not leaving the house tells me its quite nasty.
Is it possible to make a small, temporary run that can be put next to it? It would allow both sets of chickens to get to know each other before they get mixed.
Or you can move the feeders and drinkers down to the far end of the run and place some smaller ones near the front of the house for the new ones.
Failing that, you can give them time to sort it - just like any animals, there has to be a hierarchy and they're just establishing theirs.