I personally wouldn't call it defiance, be patient and feel for him. He is dealing with much more inside himself. Start a sensory diet, start looking online for different ideas. He is having a meltdown because he doesn't know how to cope. It is frustrating, believe me I know. My son is 8 now and ( not wanting to jinx myself) just last year he started getting to the point where I could relax a little. When there is a new routine, different school environment ( the start of every school year) he has a terrible time adjusting. He is seeking out what his body is craving he is annoyed by things that he cannot tolerate. Start a daily chart for him to follow with picture cards. Make it so they can be taken off once a task is completed, then if the routine changes you can change up the cards if needed. There are free sites to print them off on. Use timers as a warning as to when an activity is going to end. SPD kids have a horrible time transitioning and that can be a lot of the meltdown cause. " IN five minutes we need to clean up I will set the timer." He can finish whatever he is doing that is very important to him. Take the timer with you where you go if you have to! Weighted blankets, heavy work... have him carry in the milk, laundry soap, etc. Use his interests to your advantage. I remember this one time my son could not leave the house until he drew a diamond perfectly. We had to leave for school and he was drawing a diamond and the line would not come out perfect, he could not stop himself, he was in tears, it was so sad to see. SPD kids take things very literally, hard for them to think out of the box. There may be something they hear, smell, feel that we do not and that could be an issue as well. What is you form of punishment? I know time outs never worked with my son, sitting still was already an issue. I do , do push ups like 5 , I just recently made him an 'UH oh' box, when there is a behavior that is inappropriate he as to pick a punishment out of the box and do it. It can range from push ups to dusting. If he has a whole day without any uh ohs he gets to put a sticker on his chart and pick a reward. It works!!!!!!! I cannot express enough the visual aids!!! You need to make a mental record of what sets your child off and try and find another way to get something to work for him. For his shoes, if you know you are going somewhere, give him that warning and set the timer. It may take a few times, but it will work. He is being defiant because he cannot transition from what he is doing at the drop of a dime. Before you go somewhere give the game plan BUT always let him know that things can change and we need to be ready for it. If you have to go somewhere that requires a lot of sitting, take hi to do heavy work, run, jump, etc. get that energy out!!!! You guys will be ok, just be patient with him, he hurts and cannot help himself. You are the only people who will be his advocate for life and he needs to be able to let out his frustrations around people who won't judge him. Things will get better these kids are amazing and have amazing minds, my son is hysterical, super intelligent, loving, and extremely SESNSORY SEEKING!!!!! lol Everything will be ok!