Another thing they could do is not share information or blame something on another - deliberately or inadvertently - thinking they didn't need to know or thought it was that person that did something they shouldn't have done.
As a setting all practices should have equality and diversity policies/procedures and potential employees should be told that settings put them into practice. Having said that it is now up to a manager to make sure that is followed/practised in the setting, and it would be a pretty poor show if a manager was unconcerned that one of her staff was/may be discriminating against another.
The first thing she could do was to observe, organise something such as a social or a work activity where she could 'mix and match' staff so that there is staff cohesion - cooperative staff who respect each other make for a good team working towards the same goal with an atmosphere/ethos for the children. Staff who work with children (or any work place really) should respect and work well together at work - even if they do not socialise away from work.
If the manager saw that 'this' person was discriminating against another staff member, she would have to speak to that person, explain that it will not be tolerated - observe and monitor, but if 'that' staff member refused to follow the settings policies/procedures - it is a case for dismissal.