Backstory:

My fiancée and I have been together for 4 years, both bringing in a daughter from previous marriages. My SD's bio mom is a meth addict and got all three of her kids taken away and so we decided to move 2,000 miles away to start fresh. 
Bio mom sold my SD for $200 at one point, let's her down on a regular basis and drops off the face of the earth for sometimes 8-9 months at a time...