In my top bar hives, I have a lot of brood cells. In the spring, I add a few empty bars in the front to help prevent swarming. This just pushes the older brood cells further back.
Last year, they filled them with honey (toward the back of the hive). We took some of this honey for ourselves and it tasted pretty awful (for us anyway....maybe it's an acquired taste!). Plus, with the crush and strain method, the wax is of no use (unless you know otherwise, please tell!).
What do you do with the wax that was formally brood cells from your TBHs?
Render it down just as you would and comb. You just have to filter out the slum gum.
Scott