How can I multi-edit tasks to assign each to a different user story?

How can I multi-edit tasks to assign each to a different user story?

In Rally, it takes a few clicks in the UI to re-parent a task. When many
tasks have to be reparented it is impractical to do it one at a time. The
drop down on "Multi-Edit: Task" page allows to change Name, State,
Estimate, ToDo, and Owner but does not allow to change Work Product even
when this column is added to a custom view on a Tasks summary page.