To do this, you should keep a record and write down the tasks of each participant. And preferably you should have someone else helping you in this matter. Working with people and organizing them has always been a very difficult process. Also, for example, try using the RACI matrix. I think with its help you will have much less problems. You can find all the information you need at the link
https://www.voiset.io/blog/what-the-raci-matrix-is .