Look at topping her, lots of topics here on doing that. Its the process of cutting off the top tip of your plant which forces it to grow 2 shoots that become the main colas.
Look at LST(low stress training), again lots of topics here discussing that. Its the process of tying/bending down the top of the plant to expose the inner growth shoots to more light.
If done properly you could have 10 growth shoots at the same height instead of one.
I dont have much time right now, but if you have any further questions let me know i will check back in.