Bedtime behaviour

The hen that is top dog  keeps booting out the same 2 hens out of the coop  every night all of them are tucked up then she finally decides to retire(always last 1 in) and causes chaos..why?im sick of telling her off.
What makes it worse is that my sussex sounds like a goose so the disturbance is soooo noisy
Its been over a month now so i doubt she will stop untill maybe  other hens are introduced that she can boot out of bed instead so to speak,is this usually what happens in a coop at night?? cheers julie 

how many perches do you have and are they at different heights and locations in the house?