Where I'm from being a drug addict isn't enough to make you lose custody of your child. You have to prove that the parent is unfit due to their drug use. Also,if a parent has a spotty past the judge will look at it but they will also look at what the parent is doing with their life now and if the parent is doing well with their life and has become a law abiding citizen than the judge is going to take that into account more than his past(unless he has a really terrible past). I'm not trying to be argumentative or anything but I have been through both of those scenarios(parent being an addict and parent also having an extensive criminal history but doing well in life now) but every case is different and so is every judge. Even the child support doesn't prove that he is an unfit father but I do think the judge will take that into account. I'm positive that her SO will not be awarded full guardianship but I don't see why he wouldn't be granted partial guardianship. I also haven't looked at Ops post history so I don't know if there is more going on with her SO or anything that I don't know about. Once again,not trying to be argumentative,sorry jf it came off that way.