Hi Marco,
This is a little bit confusing so I might miss something, but I will do my best to suggest things.
The clients need some custom fields like upload file fields for notes of the coaches. The coaches will be assigned to a client. Only the coach assigned to the client can read the uploaded files in the dossier of that client. How would you approach that?
For sure clients and coaches will be separate custom post types.
You can create a view that will show the clients list and then use a filter that will work on the custom field of 'assigned coach'. If that custom field is equal to the current user that visits the page then you show the client.
In the page that you add the view above you can use Toolset access to limit it for only coaches. It is just an idea, maybe there is a better way for implementation.
Also another challenge is that the are also group sessions. In this group session the max attendees is for instance 24. They want the group to have at least 1/6 men otherwise the activity should close. How would you approach that?
You will not be able to do that with GUI features of Toolset. You might need to use WordPress hooks to programmatically check if the criteria you want is met.
For example on save_post maybe you can use PHP to check if the criteria meet or any other hook depending on when you want to do the check.
Would you use the WordPress(woocommerce) default users or create a CPT for clients.
Using default users in Woocommerce will be limited functionality wise, I would use separate post type for them.
There will be diet wishes for some clients. They can use a custom field where they can tell what kind of diet they want. I would like to have a possibility that would tell the manager of a location that there are people coming with diet wishes.
It depends when you want to add the wishlist. If you add it in the admin inside a custom field, then you will need to add a PHP code on save_post hook to for example send an email to the manager.
If you add the wishlist via a post form, then in the form you have many options to send notifications, and you can select who to send the notification to. If needed and you want a fine tuned method, you can use the Toolset Forms hooks to send the notification. Here is the hook list:
https://toolset.com/documentation/programmer-reference/cred-api/
Maybe you can use this to dynamically determine who to send a notification after the form submit:
https://toolset.com/documentation/programmer-reference/cred-api/#cred_notification_recipients
The relationships seems to be ok in my opinion.
Please consider that you ask too broad of questions and I did my best to answer them but it is not a set in stone answer you know 🙂
Thanks.
