Let’s take the history of alcoholics (family) out of the equation. Let’s take the current alcoholic (your sister) out of the equation and let’s take the codependent (you) out of the equation.
Take all the adults who are capable of seeking help for all these issues if they chose.
And who does that leave………..a very innocent and HELPLESS 4 year old.
The adults are all caught up in addictions and emotions –old and new who’s the advocate for the 4 year old?
At the very least contact your local child protective services and see what this child’s options are.