Self Management of a Very Large Group

I have been using Fibery to manage my project and now we are entering a new phase and I would like to understand the feasibility of Fibery for our new needs.

We are a participatory consumer cooperative, a community supermarket, where people organize themselves into voluntary shifts. We currently have 40 people in the project, but we should open our doors in 3 months and we will hopefully have more than 500.

I have been trying to use Fibery to organize work shifts, but it has been a bit frustrating. Let me explain. The idea is for each person to have their own login and be able to manage their shift changes and cancellations. I tried to make each person have a Guest account (since paying for 500 member users would be absolutely unfeasible. We are a non-profit supermarket). However, guests cannot press buttons or fill out forms within Fibery.

I then tried using Fibery forms on our website, so that people outside the system could enter new information (it worked perfectly for registrations). However, there is no way to guarantee that the person who entered the information is the person they say they are (there is a field on the form for a name). And I also have to rely on automations that send emails instead of having a quick response on the return screen to inform whether the shift was in fact canceled, changed or created.

So I wonder, would Fibery be a possible platform for managing the voluntary shifts of our cooperative supermarket?

Could you describe in more details what this Guest user will usually do?

This guest user would have to be able to exchange his voluntary shifts with another user. For example, he would assign one of his shifts for exchange and choose the shifts date and hour that he would be up to do. So the owners of those shifts would see on their screen that there is someone interested on exchanging their shifts. And then they would be able to accept it, for example clicking a button.

I was trying to work with this form:

“Cooperante” is a list of all the members; “Turno de Trabalho a Ser Trocado” is a list of the shifts that are scheduled. I wish that when I choose the member, the list of scheduled shifts below would show only the chosen member on the first field scheduled shifts, for example… That would be one possibility.

There is no reason why a guest cannot press a button on an entity to which they have editor access. Of course, if the button contains actions which they do not have the permission to execute, it will not be possible to do these.

What are the involved dbs, and the relations between them?