A relative of the Brooklyn man shot by NYPD cops after he stabbed his young daughter and three nieces with a meat cleaver had feared he would lose control one day — and kill everybody in the house, a police source said Monday. Months before Longqian Chen, 49, allegedly attacked the four girls Sunday with a meat cleaver and large knife in their Bensonhurst home the relative filed a complaint with the city’s Administration for Children’s Services describing him as potentially dangerous to family members, police sources said. Click here to read more on nydailynews.com.