Sub-item permissions

We need a sub-item permission level when configuring the board permissions, our use case will be a training record for our employees, the main item will be the Training Title and the assigned person will be the trainer, sub-items will be each one of our employees,

subitem name: Employee Name
subitem persona column: User selected
subitem status: attended / did not assist

The feature request is to allow every employee to edit their own subitem and not to alter other subitems that dont belong to.

This cant be done without subitem level permissions.

We would be very interested in having subitems permissions as well!