These three unnamed witches were members of the Grand Coven.
Background
Rowena attempted to recruit these three witches as members to her new coven, the Mega Coven, on the grounds that their former coven was falling apart.
To convince them to join, Rowena boasted that she had killed her own son, the King of Hell, by commanding an angel to do it. However, one of the witches had made a deal with Crowley not long ago, much to Rowena's confusion.
The witches attempted to leave Rowena, driving the witch to use a spell from the Book of the Damned and kill all three.