I agree with the previous post. You need to be honest with her she is old enough to know who her birth father is. Just tell her that he had made some bad choices in life and is trying to do the right thing now and wants to be in her life. And maybe when she gets older (if you don't tell her now) the reason that he was not in her life before because of drugs, but she may understand that now, you will have to decide that one for your self if you think your daughter should know that part of his life. It is better to hear this from you than from someone else. Good luck!!! I hope I could be of some help.
Hi--I have three birth children and two adopted children. Both the adopted children were foster children we had and we have had many many others in our home. I also work with foster and adopted children. Both have always known they were adopted. One of them is very interested in every detail (Birth mom was a meth addict, no birth father on the certificate, etc) and I am very honest with her, the other is not. First do NOT use the word "REAL" that means the other one is "Imaginary". Use "Birth" and "Adopted"--be honest, tell her your job is to keep her safe and that her birthdad was making bad choices at the time and her adopted dad loved her so much and wanted to keep her safe that he adopted her. Just be open, and straight forward and don't put it off any longer--tell her you probably should have told her earlier, but you did not and now you are. Good Luck---Kids are smart and love your honesty! Take care.