Nannies and Abusive bosses

[LouIsOnAHighwayToHell]

I have been talking with a nanny friend who believes her dad boss is abusing her mum boss. There is a lot of verbal abuse and now pushing and shoving. The nanny feels that she should not get involved. This is her first experience with abuse. She wants to do something but is not sure what. SHe was going to quit but now feels that she can't due to the situation.
Is there someway she can report what is happening without the parents finding out (all very hush hush kind of people - don't air the dirty laundry)?

The mother is a SAHM who has three kids but has a nanny and cleaner. THe nanny is underpaid and over worked which is why we finally convinced her to look for a new job but now she feels she must stay becuase of the DC's. She does not feel comfortable talking to the boss about it. They do not have that kind of relationship.
The mother has called a helpline but no idea what else has been done.

She is staying for that reason and becuase she is scared to make a change in her own life (but that is another story). I will tell her to make notes about everything.
Thanks for your advice.

Verbal abuse within a relationship is instantly classified as domestic violence by the police. If you called them they'd want your name although they wouldn't disclose it if you asked them not to. The issue with it is that unless there are visible signs of abuse then the police won't be able to do anything about it on the say-so of a 3rd party, so I think it depends on whether you think a visit from the police would shake DB up enough to stop?