Squash & Strech // Puppet

[GAGALINETTE]

Hello everyone, it's my first post on this forum so sorry if i do some mistake (i'm french, i don't talk english very well)...My question is following, i would like to use an expression for doing an "squash & stretch" on my puppet (i use an "warping bezier" effect). When i move up and down my "Top" null object, both Side (Left_Side null object & Right_Side null object) move outside or inside with proportional ratio.




Thank you.