Are we really safe when raising childeren?

I live with my father and he was caring for my nephew because his mother who happens to be my sister decided she wanted to abandon him while he was a new born so to cut it short my dad took custody of his grandchild. Fast forward about 3 1/2 years later my sister comes back into the picture and starts a whole bunch of drama while living with us. She was eventually removed by the police and shortly thereafter she starts calling children’s' aid in Alberta and telling them lies about abuse in our household. They came here and did their little investigation found nothing and gave my dad information on how to get emergency custody of his grandchild. On June 1st later that evening Children’s' services of Alberta came with around 4 police officers trying to intimidate us with their guns and forcefully dragging my nephew out of the house while he was screaming and crying he does not want to go. Is it fair for CW to drag kids out of the home with false pretenses because the mother is a known liar