I have full legal custody of my grand-niece. How do I deal with the biological mother randomly popping up at holiday time pretending she now cares?

I've had full legal and physical custody of my 4 year old grand-niece, let's call her abbie, for 2 years now. She is a part of our family and we are looking to eventually adopt her once it's legally "easier". The Abbie hasn't been with her biological parents for 3 years now. They are both drug abusers and aren't really a part of her life. The parents aren't together anymore, and they lost their second child in April, who is now with a foster family (doing really well, might I add).The bio father hasn't seen Abbie but once in almost 2 years. The bio mother hasn't seen her in 13 months, nor has she even spoken to her on the phone since last Christmas. Every time I try to plan a visitation with the bio mom (my niece), she either cancels or just never follows through. I've heard from various people that she speaks very ill of me, to make me look like I am the one who won't let her have contact when that is far from the truth.I am starting to get very nervous about the inevitable contact from the bio mom to see Abbie for Christmas. I don't even know what is morally right anymore in terms of contact and visitation. The bio mother is a drug user, doesn't have a job, has never contributed to Abbie and I honestly don't trust her at all in any context. We try very hard to make Christmas, as well as every holiday, very special and stress free. Last Christmas when the bio mother called and spoke with Abbie, Abbie became very upset and wouldn't speak with anyone except me for a couple hours after. I honestly don't know what her reaction to speaking to or seeing her bio mother would be but I'm afraid it would be negative.How should I deal with it when the bio mother contacts me? Should I allow her to see her simply because it's Christmas, or should I make her prove she's clean from drugs? I'm 100% not Ok with her taking her somewhere with her. Ugh, I just hate the stress. Even with stipulations, nothing is ever good enough for her and it starts a fight. How do I handle this? via /r/Parenting http://ift.tt/2g33H8Z