Is this possible?

I have a membership portal of which I need to create a date for each of the members to complete duties at the club.

What I want to achieve is 6 members to be selected at any one time and then for it to the next week select another 6 members (without repeating the previous ones)
Once all the members have been selected I need it to reset and then start all over again.

Ideally I would like this to be automated, I can figure a way of doing it manually, but is this even possible to do automatically ??