Do you know the way to update or override for existance tasks with Project Task Import(FBDI)?

Summary:

Do you know the way to update or override for existance tasks with Project Task Import(FBDI)?

We create tasks for Existance Project with the following FBDI template as solution of Project.

When I tried to validate that can we update partically imformation(ex.DFF-Coulumn of Attribute) for existance tasks, it is failed and the error message was appeared like It is not possible to add tasks about existance tasks in reject report .

If you know another way?

Thanks,

Mayuko