Milestones and tasks - calculating completion %

[Taskmaster]

I am using the Gantt view. 

I have 50 tasks. Every 10 tasks has a milestone.  And each set of tasks is marked as dependencies for each milestone they come under. 

I would like the milestone dates to be updated automatically when the end dates for one of the 10 tasks change. i.e the task with the furthermost date should be the end date of the milestone. 

How would I do this ?

Thank you !

[TheTimeSavingCo]

Hm I don't think I understand.  If all your tasks and milestones are dependency linked, then this should happen automatically, no?