question about bringing Adderall XR

I am heading to Bali next week with my 2 kids and have a question about medication I hope someone can help me with. My son has a couple of medical conditions and one medicine he takes is Adderall XR. It is my understanding that it is considered “illegal” in Bali. I have letters from his doctors for all of his prescription medicine. I will take only what he needs for the month we are there and in the original containers. I will declare it upon arrival. Will this be enough to get it in for him…AND not have any trouble in customs? I am worried that we will get a customs agent having a bad day! What is the worst case scenario since I am declaring it…will they just take it from us, fine us or arrest us? Thanks for any advice!!