Okay im not getting a rat becaus ei already have 6 ( 2 boys 4 girls )

Okay so my girls are split into 2 groups ( 2 are in one cage and 2 in the other )
they all came from the same breeder but i bought them at different times so theres an age gap between them.

Im trying to introduce the 2 newest one into the other 2 cage but my Russian Blue Dumbo ( Ercila ) is having none of it they scratches the hell out of my poor little Naked ( Mortisha ).

---Ive tried letting them out together in the bath tub = they are fine with each other
---Cleaning the whole cage out then putting all four in = Ercila beating everyone including her cage mate.

Im about try and bath them all so they smell the same and clean the cage out again hopefully this will work.

but do you have any other suggestions ?