Is anyone know how multisign transaction works? I am interesting in case 2 of 3 signs for work. For example, my system has 2 users (A and B) and SERVICE. How to make multisign transaction between members?

Hello there. I am an engineer of blockchain exchange. And recently we want to add STEEM to our exchange. I search the Internet for the use of Steem. But there is not much info about it. I have read the