1) contrary to common misperception, butterfly does not
require extremely strong ab muscles. you need strong
arm strokes and in-sync with hip/leg/head movement;
2) butterfly is an extension of breaststroke, it is one
of the two families. Crawl and backstroke in one,
butterfly and breaststroke another, so perfect your
breaststroke first;
3) your breaststroke has to be good enough such that
as you contract your arms and legs and extend your
head, your body is naturally shooting up out of
water;
4) then, instead of constrasting arms, alter the
breaststroke arm movement to a complete circle
close to your ab then extend out of water
5) your legs can continue to do the breast stroke
kicks, no need for dolphin first
6) once you are flying well, start to do the 2 kick
dolphin moves, here is the trick to convert:
keep legs extended
move your butt up and down
when butt down, legs up,
when butt up, legs down,
bend knee a little to help legs move
7) so here is a complete circle,
starting arms and leg stretch straight line, head down
butts up, arms start breaststroke like circle, head down
butts down, arms finishing circle, bend knees,head down
butts up again, kick down, arms fly, head up,
glides
head down, arm go straight, leg keeps straight,
start another circle

Now, Hunhun, once you can do this and impresses a
YN, you have to show us the picture of YN.