Re: Splitting bees from Top Bar to Langstroth
Yes, I'd make the split into the Lang as your friend is taking away the TBH. Shake a bar or two of bees from the TBH into the Lang as you make the split, choose bars with open brood to shake from as they will be mostly nurse bees on the frame to shake into your queen right Lang. Leave the Lang in the same spot, or close to it, where the TBH was. You should get a decent shook swarm split in the Lang, and your friend will get a queenless split that should make a queen of their own.
20+ years, raise my own queens, feed when needed. I treat, but have not perfected varroa management yet.