If you're talking about half-butterfly guard, I don't really have anything for you.
If you are looking for ways to transition into butterfly from half guard, then I have some options you can explore.
If you can get an overhook and feed their cross lapel, you can hip out to make space for your top leg, then put your top hook in, scoot your hips back again, square up and push into them to get your next hook in.
If you have the underhook, if they pull back, I can often follow them up and insert my top hook there.
Also, someone posted this on r/bjj, but it's a nice technique from bottom half which results in your basic butterfly sweep.
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This technique compliments the above fairly well.
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Aesopian put out a vid related to Kurt's vids, plus a few more related options:
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