If I’ve got this right, the child currently is in official custody of the (unemployed) mother, who lives with a boyfriend, and both of them have drug and alcohol abuse issues, including an arrest for the mother (and no noted documentation of the boyfriend’s issues). The boyfriend’s employment should not be an issue, but it’s noted that he is also unemployed. The child lives with its maternal grandmother, and the father has not been paying full child support payments, which has led to the court hearing on that topic.
I don’t know where people are getting the idea that the father, your boyfriend, has a record (unless that’s from an earlier question that I haven’t seen), but it would seem completely reasonable that he should request the drug test for the custodial parent, and that he should seek custody – good luck to him. He can’t just interrupt the judge’s docket with an accusation or request, however. If the hearing has already been scheduled to consider his lack of support payments, then that’s what the judge is going to want to know about first of all.
Once that matter is heard, then he can make his request / accusation. Unless he has had a history of having the child stay with him in unsupervised visitation, I can’t even imagine a court overturning the custody arrangements summarily, especially since a drug test – even if administered on the spot – would probably take time to analyze and be entered into the record. If he has had unsupervised overnight visitation with the child (he’s not considered to be a danger, in other words, and his home environment with you is documented in some way as being acceptable to the court), then he may be awarded temporary custody pending the outcome of the additional hearing. Maybe. (On the other hand, if the child is living with grandmother in a good environment and not subject to the mother’s and boyfriend’s problems, then I doubt if any change would be made – unless the grandmother supports that request.)
I expect that if grandmother shows up for the hearing then the judge will start the procedings by considering the support payment issue that is currently on the agenda and take the motion to consider the mother’s fitness to retain custody. Unless your boyfriend brings documentation or other proof to court that the child is at imminent risk, the judge will not make any hasty decisions on custody. I would expect that if he’s competent and Child and Family Services is on the ball, that he’ll order an investigation into the mother’s and child’s living arrangements and consider further motions on custody later on, when he receives a report from a CFS agent.
Your boyfriend should have an attorney. It would also be helpful if he has a good relationship with the grandmother (and the child, obviously!) and can get her to advocate for him. That’s his best chance. It’s unlikely in the extreme that he will be able to swing all of this by himself.