Maybe I'm not exactly understanding the issue. Correct me if I'm wrong, but it sounds like you want your BB to stay put as the tractor moves/angles up and down over the terrain yes? So you're basically trying to scrape off the high spots and deposit the material in the low spots.
I would think using chains might actually make things worse. I would think the chains would be so loose they cause the BB to simply float/glide over bumps more easily no?
As N80 said, the best approach is to man-handle your 3pth lever and travel along the length of the high spots scraping them off. But that is often not possible, like a lot of areas on my driveway.
Does your tractor have a float position for your 3pth? Mine does and what works well for me is to open up the 3pth valve so it moves very freely in float and I added a boat load of weight, in the form of big rocks, to my BB. With my set up like this as the tractor angles up, say coming out of a low spot, the float (and gauge wheels) allows the BB to not dig in. As the tractor angles down, going into a low spot, the added weight and free movement of the float keeps the BB pretty much level and plowing through the high spot scraping it off.
One thing to keep in mind about BB's, it often takes a lot more passes than you think or want to do

That was my biggest learning curve. Pass after pass is often times needed to get the results you want.
j