The problem you are having is first and foremost your light must be way way too far away from the tops of the plants because they are stretching like there's no tomorrow. You're going to have a whole lot of stalk with tiny buds here and there.
No amount of topping and training is going to fix that. The only other thing that can make a plant stretch this much is having way too little of a light to begin with.
Get the light where it should be, which is as close as you can before she burns. I bet you have it at least 4x further away than it should be if it's not just incredibly too small to begin with, could be on the ceiling the way they look.
And no, it won't hurt a plant even if the stalk is half way broken off, as long as it is still connected it will recover just fine. But, I see HPS light, so maybe you are starting flowering? If so you don't want to shock the plants with any trimming or training you don't have to do. It will stunt her growth in the worst time possible.
Next time around you'll shit yourself at how much faster they're growing, how different they look, and how much more yield you end up with when you keep the lights as close as you can all the way though.