Note how potentially criminal the logic here is.
The “stage mom” allows her “daughter” to drink from such a cup, so she should be murdered (and having her stage daughter taken from her).

*However* this implies that according to Nolte the real mother deserves the same fate, because she allowed her real daughter to drink from such a cup for the sake of filming this episode. Maybe Nolter did not even intend this, but it is what it is.