Re: Moving from Commercial to Top Bar
I wouldn't cut your commercial combs to go in the TBH, as part of the TBH philosophy is natural comb.
Since you are concerned about losing brood from the commercial frames, one way would be to make up top bars that could be fitted in a commercial box. Alternate a few of them through your commercial hive to get a few top bar combs built. Then put these top bars, and the queen, in a box above an excluder over your brood box. 3 weeks later all brood is in your top bar combs, and transfer to your TBH.
Having said all that, I agree with the other posters. Don't throw out your commercial gear yet!
"Thinking Inside The Box"