If you make your top bars the same length as the lang frames, you can hang 3 or 4 in between brood combs in your lang. If b is brood comb and t is top bar, it should look something like this: bbtbtbtbtb. Make sure that the bees can fill out the spaces below the top bars. The bees will start drawing them out and the queen usually cannot resist laying in new wax. If they don't start drawing it right away, feed them a little syrup, but this time of year you should have no issues getting them to draw it.
In couple of days you will have some comb built with young brood. Gently transfer that to your lang and then shake some extra bees from the rest of the brood combs. Expect that some of the comb may be attached to the sides or bottom, depending on how quickly they draw it. Make sure you feed (patty + syrup). Personally, I would also transfer the queen and let the stronger hive (the lang) raise a new queen.
In this way you will start with straight comb which is a major plus.
In couple of days you will have some comb built with young brood. Gently transfer that to your lang and then shake some extra bees from the rest of the brood combs. Expect that some of the comb may be attached to the sides or bottom, depending on how quickly they draw it. Make sure you feed (patty + syrup). Personally, I would also transfer the queen and let the stronger hive (the lang) raise a new queen.
In this way you will start with straight comb which is a major plus.