To clarify my earlier post - giving choices helped us because it lowered the number of battles we had to go through in a day and let me pick the ones that mattered and had real lines I didn't want crossed. I don't care if he eats and apple or a banana so I gave him the choice and let him feel like he had some control for parts of his life which in turn made him less confrontational about the parts of his life he had no control over. When we did have battles then I fully agree with the above posts (not engaging, strict boundaries, extremely consistent rules). Once he did dig then there was no negotiating or options because as pointed out they will find new ways to push the boundaries.
