So for creating a new task, you have to fill a form right ?
Selecting the métier type
Then Selecting or creating the project [Unique ID Project]
And finally adding one or more task to the project [Unique ID Task]
So the Row condition expression of the Tache Slice should be :
For example, [_THISROW-2].[Phone] retrieves the value of the Phone column of the grandparent Table.
[_THISROW] => Goes up to the top level.
[_THISROW-1] => Goes up one level to the “Parent”.
[_THISROW-2] => Goes up two levels to the “Grandparent”.
[_THISROW-3] => Goes up three levels to the “Great Grandparent”.
[_THISROW-n] => Goes up n levels.
To reach your Grand parent table [Métier] its [_THISROW-2]