Divide consumption between three tenants

Hello everyone, I’m new to the forum and the Home Assistant system. I installed the system on a Raspberry pi3 with the version recommended by the imager. My need is to record the consumption of a washing machine used by 3 different people in order to divide the energy costs. I installed a SHelly 1PM that controls the washing machine and I created 3 users in the Home Assistant server. Now I need to be able to record the consumption of the washing machine based on the user who activates the switch. I followed several tutorials but I can’t configure the system. Can someone help me. Thanks

Create an number helper for each user, one utility meter that you can reset and an input select(dropdown) which resembles the last user. Put the energy sensor as the source of the utility meter and make an automation, that when a switch is pressed, the right number helper (chosen by the dropdown value) gets raised to the old value + the utility meter value. Then reset the utility meter and set the dropdown to the current user.

Another one would be to add an utility meter with 3 tarrifs then change the active tarrif according to the switches.
I included the first one as I havent used tarrifs yet and am not 100% sure it works that way, but you can test that easily.