We have two little ones (ages 2 and 4) with special needs. They also were affected by substances, have cognitive impairments and language challenges. One is autistic and the other has different issues. I understand just how difficult it can be to discipline a child with special needs.
I'm still working on it myself, but one tip I can share is to think about the age at which the child functions. My 4-year-old functions more like a 2-year-old, so I try (hard as it is) to think of his behavior as that of a 2-year-old even though his body is much bigger. That means that while I might expect a typical 4yo to follow directions, control impulses, sit still sometimes, etc., I try not to expect that my son will be able to do that as much.
The hard part is balancing that with remembering that he *is* capabale of doing some things and that I can't expect him to advance if my expectations are too low.
My 2yo has Fetal Alcohol Syndrome, which might (I'm not sure) affect behavior in a way similar to meth. He has an incredibly hard time understanding cause and effect. It is not just him, but a common feature of FAS. Another child might realize that if he throws his cup over the fence, it is gone, but mine does not. He literally does this dozens of times a day and cannot understand he caused the loss of his own cup. It is not just a game, but a very real effect of the brain damage caused by the alcohol.
Early On professionals taught me to use very simple words with my sons. With my neurotypical daughters, I liked to explain things a bit more. Even when they were toddlers, I would tell them, "We don't hit. Your friend is sad because you hit him. He doesn't want to play with you because you hurt him. Let's stomp our feet if we're mad instead of hitting." With my sons, I learned that their brains do not process a barrage of words. It makes things worse because it overstimulates and confuses them. For them, I simplly say, "No hit." As they grow I'm sure I'll add words, but for now this is all they can seem to process.
I am a proponent of gentle loving guidance (natural consequences, empathizing with children, no hitting, offering choices, distracting and redirecting rather than punishing, etc.). It was very hard for me to make this work with my boys. I picked up some parts of Love & Logic (it is more gentle these days than the original versions, or so I'm told). Consistency is beginning to work with my 2yo. He could not understand explanations about hitting and did not seem to understand that his actions were causing the other kids to want to get away from him (he loves to be with kids). I have starfted to say, "No hit. If you hit you need to sit in your highchair. He hates being confined, so it is beginning to work, but as soon as my hands are full and I can't immediately get him to his chair when he hits, it's like he has unlearned it.
My 4yo with autism also laughs inappropriately. One of the other kids will get hurt and cry and he'll laugh. We are trying to teach him emotions. We have board books with pictures of babies making different faces. We'll show him happy baby, sad baby, and we are trying to label his emotions. "You are sad because you fell down. You are crying." "You are mad because he took your toy." "Look! Brother is happy because you shared Elmo!"
I hope this helps. It is such a balancing act to manage inappropriate behaviors while not being more harsh than their abilities allow or so easy on them that we're doing them a disservice.
Are there any specific behavior situations we can help you with? Maybe we can brainstorm with you (and I can learn along with you!).