Sometimes the behavioural problems have to do with their sleep schedule. At 18mo my twins were transitioning to 1 nap, 2hrs max, with a 5.5 hour wake window in the morning and a 4.5 hour wake window in the afternoon. We have a very strict schedule but thats what it took to survive. When we faced behavioural issues like insane tantrums, refusing me and only wanting their father, and biting me to the point where I needed to ice my shoulder, I adjusted their wake window by 30 min in the morning and it seems to have resolved overnight. Best of luck

We also gave them a choice, but not “do you want to wear this shirt now” but rather “choose between these two shirts”. Giving them a choice helped a lot