Would you call CPS on your own family for drinking to much ?

There are 3 solutions to this scenerio. One, you confront your sister in law by not stating her fault, but by concerning her that the nieghbors are coming around the house, leading her to take more action and being more protective around her daughter. Two, call social services autonomously to examine the situtation (the parents will have a chance to improve for the sake of their daughter). Three, Ask for legal guardian rights. The same way it goes through social services, and if the parents do not improve their ways, you being a relative, can take custody of the child. Once again, ask to remain anonomous so you dont get blamed for their bad behavior.