How to refresh the parent form attributes when activites are marked as complete.

Hi

I want to do the following tasks on the Parent form when user completes the activities (email /phone call) either from the Sub-grid (shown on the parent form under Activities) or open the task and perform “mark as complete”

1. Update the parent form attributes (on the Header and Body sections) and refresh the form to show the current values to the user.
2. Show/Hide some buttons on the Ribbon bar

Currently I am updating the parent record using the Plugin & Workflow (when the task is completed) but CRM takes its own time to update (if a workflow) and user has to continuously refresh the screen (Press F5) to see the new values and the new Ribbon bar buttons which is really annoying , Can you please suggest the best way to do this ?

MSK