looking for advice

Hello This is a problem I have come across over the last few days. I have 12 ladies, 6 are isa warrens 3 speckled hybreds and 3 blue hybreds, I have had the warrens since March, The other 6 I got 3 weeks ago I had the normal pecking order battles but nothing too serious, The problem I have got is that a blue hybred is attacking a couple of warrens when they go into the nest box to lay, has anyone got any ideas of how I can stop this please................
 Thanks in advance

Yes I have 5 nest boxes, She is following then into the coop, Its not as though she's wanting to lay herself.